sin_cos7.miz



    begin

    reserve x,y,t for Real;

    

     Lm1: number_e <> 1 by TAYLOR_1: 11;

    

     Lm2: (x ^2 ) < 1 & y < 1 implies ((x ^2 ) * y) < 1

    proof

      assume that

       A1: (x ^2 ) < 1 and

       A2: y < 1;

      per cases by XREAL_1: 63;

        suppose 0 = (x ^2 );

        hence thesis;

      end;

        suppose 0 < (x ^2 );

        then (y * (x ^2 )) < (1 * (x ^2 )) by A2, XREAL_1: 68;

        hence thesis by A1, XXREAL_0: 2;

      end;

    end;

    theorem :: SIN_COS7:1

    

     Th1: x > 0 implies (1 / x) = (x to_power ( - 1))

    proof

      assume x > 0 ;

      

      then (x to_power ( - 1)) = ((1 / x) to_power 1) by POWER: 32

      .= (1 / x) by POWER: 25;

      hence thesis;

    end;

    theorem :: SIN_COS7:2

    x > 1 implies ((( sqrt ((x ^2 ) - 1)) / x) ^2 ) < 1

    proof

      

       A1: (( - 1) + (x ^2 )) < ( 0 + (x ^2 )) by XREAL_1: 6;

      assume x > 1;

      then (x ^2 ) > ((1 ^2 ) + 0 ) by SQUARE_1: 16;

      then

       A2: ((x ^2 ) - 1) > 0 by XREAL_1: 20;

      ((( sqrt ((x ^2 ) - 1)) / x) ^2 ) = ((( sqrt ((x ^2 ) - 1)) ^2 ) / (x ^2 )) by XCMPLX_1: 76

      .= (((x ^2 ) - 1) / (x ^2 )) by A2, SQUARE_1:def 2;

      hence thesis by A2, A1, XREAL_1: 189;

    end;

    theorem :: SIN_COS7:3

    ((x / ( sqrt ((x ^2 ) + 1))) ^2 ) < 1

    proof

      

       A1: (x ^2 ) < ((x ^2 ) + 1) by XREAL_1: 29;

      

       A2: (x ^2 ) >= 0 by XREAL_1: 63;

      

      then (( sqrt ((x ^2 ) + 1)) ^2 ) = ( sqrt (((x ^2 ) + 1) ^2 )) by SQUARE_1: 29

      .= ((x ^2 ) + 1) by A2, SQUARE_1: 22;

      then

       A3: ((x / ( sqrt ((x ^2 ) + 1))) ^2 ) = ((x ^2 ) / ((x ^2 ) + 1)) by XCMPLX_1: 76;

      per cases by XREAL_1: 63;

        suppose (x ^2 ) > 0 ;

        hence thesis by A1, A3, XREAL_1: 189;

      end;

        suppose (x ^2 ) = 0 ;

        hence thesis by A3;

      end;

    end;

    theorem :: SIN_COS7:4

    

     Th4: ( sqrt ((x ^2 ) + 1)) > 0

    proof

      (x ^2 ) >= 0 by XREAL_1: 63;

      hence thesis by SQUARE_1: 25;

    end;

    theorem :: SIN_COS7:5

    

     Th5: (( sqrt ((x ^2 ) + 1)) + x) > 0

    proof

      per cases ;

        suppose x > 0 ;

        hence thesis by Th4, XREAL_1: 29;

      end;

        suppose

         A1: x <= 0 ;

        (x ^2 ) < ((x ^2 ) + 1) by XREAL_1: 29;

        then ( sqrt (x ^2 )) < ( sqrt ((x ^2 ) + 1)) by SQUARE_1: 27, XREAL_1: 63;

        then ( - x) < ( sqrt ((x ^2 ) + 1)) by A1, SQUARE_1: 23;

        hence thesis by XREAL_1: 62;

      end;

    end;

    

     Lm3: 1 <= x implies ((x ^2 ) - 1) >= 0

    proof

      assume 1 <= x;

      then (x ^2 ) >= (1 ^2 ) by SQUARE_1: 15;

      then (1 + ( - 1)) <= ((x ^2 ) + ( - 1)) by XREAL_1: 6;

      hence thesis;

    end;

    theorem :: SIN_COS7:6

    y >= 0 & x >= 1 implies ((x + 1) / y) >= 0 ;

    theorem :: SIN_COS7:7

    

     Th7: y >= 0 & x >= 1 implies ((x - 1) / y) >= 0

    proof

      assume that

       A1: y >= 0 and

       A2: x >= 1;

      (x + ( - 1)) >= (1 + ( - 1)) by A2, XREAL_1: 6;

      hence thesis by A1;

    end;

    theorem :: SIN_COS7:8

    

     Th8: x >= 1 implies ( sqrt ((x + 1) / 2)) >= 1

    proof

      assume x >= 1;

      then (x + 1) >= (1 + 1) by XREAL_1: 6;

      then ((x + 1) / 2) >= 1 by XREAL_1: 181;

      hence thesis by SQUARE_1: 18, SQUARE_1: 26;

    end;

    theorem :: SIN_COS7:9

    

     Th9: y >= 0 & x >= 1 implies (((x ^2 ) - 1) / y) >= 0

    proof

      assume that

       A1: y >= 0 and

       A2: x >= 1;

      ((x ^2 ) - 1) >= 0 by A2, Lm3;

      hence thesis by A1;

    end;

    theorem :: SIN_COS7:10

    

     Th10: x >= 1 implies (( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) > 0

    proof

      assume

       A1: x >= 1;

      then ((x - 1) / 2) >= 0 by Th7;

      then

       A2: ( sqrt ((x - 1) / 2)) >= 0 by SQUARE_1: 17, SQUARE_1: 26;

      ( sqrt ((x + 1) / 2)) >= 1 by A1, Th8;

      hence thesis by A2;

    end;

    theorem :: SIN_COS7:11

    

     Th11: (x ^2 ) < 1 implies (x + 1) > 0 & (1 - x) > 0

    proof

      assume (x ^2 ) < 1;

      then ( - 1) < x & x < 1 by SQUARE_1: 52;

      hence thesis by XREAL_1: 148, XREAL_1: 149;

    end;

    

     Lm4: (x ^2 ) < 1 implies ((x + 1) / (1 - x)) > 0

    proof

      assume (x ^2 ) < 1;

      then (x + 1) > 0 & (1 - x) > 0 by Th11;

      hence thesis;

    end;

    theorem :: SIN_COS7:12

    

     Th12: x <> 1 implies ((1 - x) ^2 ) > 0

    proof

      assume x <> 1;

      then 0 <> (1 - x);

      hence thesis by SQUARE_1: 12;

    end;

    theorem :: SIN_COS7:13

    

     Th13: (x ^2 ) < 1 implies (((x ^2 ) + 1) / (1 - (x ^2 ))) >= 0

    proof

      assume (x ^2 ) < 1;

      then

       A1: 0 < (1 - (x ^2 )) by XREAL_1: 50;

      (x ^2 ) >= 0 by XREAL_1: 63;

      hence thesis by A1;

    end;

    theorem :: SIN_COS7:14

    (x ^2 ) < 1 implies (((2 * x) / (1 + (x ^2 ))) ^2 ) < 1

    proof

      assume (x ^2 ) < 1;

      then ((x ^2 ) + ( - 1)) < (1 + ( - 1)) by XREAL_1: 8;

      then (((x ^2 ) - 1) * ((x ^2 ) - 1)) > ( 0 * ((x ^2 ) - 1));

      then

       A1: (x ^2 ) >= 0 & (((((x ^2 ) ^2 ) - (2 * (x ^2 ))) + 1) + (4 * (x ^2 ))) > ( 0 + (4 * (x ^2 ))) by XREAL_1: 8, XREAL_1: 63;

      (((2 * x) / (1 + (x ^2 ))) ^2 ) = (((2 * x) ^2 ) / ((1 + (x ^2 )) ^2 )) by XCMPLX_1: 76

      .= ((4 * (x ^2 )) / ((((x ^2 ) ^2 ) + (2 * (x ^2 ))) + 1));

      hence thesis by A1, XREAL_1: 189;

    end;

    theorem :: SIN_COS7:15

    

     Th15: 0 < x & x < 1 implies ((1 + x) / (1 - x)) > 0

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      (x ^2 ) < x by A1, A2, SQUARE_1: 13;

      then (x ^2 ) < 1 by A2, XXREAL_0: 2;

      hence thesis by Lm4;

    end;

    theorem :: SIN_COS7:16

     0 < x & x < 1 implies (x ^2 ) < 1

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      (x ^2 ) < x by A1, A2, SQUARE_1: 13;

      hence thesis by A2, XXREAL_0: 2;

    end;

    

     Lm5: 0 < x & x < 1 implies 0 < (1 - (x ^2 ))

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      (x ^2 ) < x by A1, A2, SQUARE_1: 13;

      then (x ^2 ) < 1 by A2, XXREAL_0: 2;

      then ((x ^2 ) - (x ^2 )) < (1 - (x ^2 )) by XREAL_1: 9;

      hence thesis;

    end;

    theorem :: SIN_COS7:17

     0 < x & x < 1 implies (1 / ( sqrt (1 - (x ^2 )))) > 1

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      

       A3: 0 < (1 - (x ^2 )) by A1, A2, Lm5;

      then

       A4: 0 < ( sqrt (1 - (x ^2 ))) by SQUARE_1: 25;

      (x * x) > ( 0 * x) by A1;

      then ((x ^2 ) * ( - 1)) < ( 0 * ( - 1));

      then (( - (x ^2 )) + 1) < ( 0 + 1) by XREAL_1: 8;

      then ( sqrt (1 - (x ^2 ))) < 1 by A3, SQUARE_1: 18, SQUARE_1: 27;

      hence thesis by A4, XREAL_1: 187;

    end;

    theorem :: SIN_COS7:18

    

     Th18: 0 < x & x < 1 implies ((2 * x) / (1 - (x ^2 ))) > 0

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      (x ^2 ) < x by A1, A2, SQUARE_1: 13;

      then (x ^2 ) < 1 by A2, XXREAL_0: 2;

      then

       A3: ((x ^2 ) + ( - (x ^2 ))) < (1 + ( - (x ^2 ))) by XREAL_1: 8;

      ( 0 * 2) < (x * 2) by A1;

      hence thesis by A3;

    end;

    theorem :: SIN_COS7:19

    

     Th19: 0 < x & x < 1 implies 0 < ((1 - (x ^2 )) ^2 )

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      (x ^2 ) < x by A1, A2, SQUARE_1: 13;

      then (x ^2 ) < 1 by A2, XXREAL_0: 2;

      then ((x ^2 ) + ( - (x ^2 ))) < (1 + ( - (x ^2 ))) by XREAL_1: 8;

      hence thesis;

    end;

    theorem :: SIN_COS7:20

     0 < x & x < 1 implies ((1 + (x ^2 )) / (1 - (x ^2 ))) > 1

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      (x ^2 ) < x by A1, A2, SQUARE_1: 13;

      then (x ^2 ) < 1 by A2, XXREAL_0: 2;

      then

       A3: ((x ^2 ) + ( - (x ^2 ))) < (1 + ( - (x ^2 ))) by XREAL_1: 8;

      ( 0 * x) < (x * x) by A1;

      then (( - (x ^2 )) + 1) < ((x ^2 ) + 1) by XREAL_1: 8;

      hence thesis by A3, XREAL_1: 187;

    end;

    theorem :: SIN_COS7:21

    1 < (x ^2 ) implies ((1 / x) ^2 ) < 1

    proof

      assume

       A1: 1 < (x ^2 );

      then (1 / (x ^2 )) < ((x ^2 ) / (x ^2 )) by XREAL_1: 74;

      then ((1 ^2 ) / (x ^2 )) < 1 by A1, XCMPLX_1: 60;

      hence thesis by XCMPLX_1: 76;

    end;

    theorem :: SIN_COS7:22

    

     Th22: 0 < x & x <= 1 implies (1 - (x ^2 )) >= 0

    proof

      assume that

       A1: 0 < x and

       A2: x <= 1;

      

       A3: (x - 1) <= (1 - 1) by A2, XREAL_1: 9;

      per cases by A3;

        suppose (x - 1) < 0 ;

        then ((x - 1) + 1) < ( 0 + 1) by XREAL_1: 8;

        hence thesis by A1, Lm5;

      end;

        suppose (x - 1) = 0 ;

        hence thesis;

      end;

    end;

    theorem :: SIN_COS7:23

    

     Th23: 1 <= x implies 0 < (x + ( sqrt ((x ^2 ) - 1)))

    proof

      assume

       A1: 1 <= x;

      then ((x ^2 ) - 1) >= 0 by Lm3;

      then 0 <= ( sqrt ((x ^2 ) - 1)) by SQUARE_1:def 2;

      hence thesis by A1;

    end;

    theorem :: SIN_COS7:24

    

     Th24: 1 <= x & 1 <= y implies 0 <= ((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1))))

    proof

      assume that

       A1: 1 <= x and

       A2: 1 <= y;

       0 <= ((y ^2 ) - 1) by A2, Lm3;

      then

       A3: 0 <= ( sqrt ((y ^2 ) - 1)) by SQUARE_1:def 2;

       0 <= ((x ^2 ) - 1) by A1, Lm3;

      then 0 <= ( sqrt ((x ^2 ) - 1)) by SQUARE_1:def 2;

      hence thesis by A1, A2, A3;

    end;

    theorem :: SIN_COS7:25

    

     Th25: 1 <= y implies 0 < (y - ( sqrt ((y ^2 ) - 1)))

    proof

      assume

       A1: 1 <= y;

      then (1 * y) <= (y * y) by XREAL_1: 64;

      then 1 <= (y ^2 ) by A1, XXREAL_0: 2;

      then

       A2: (1 - 1) <= ((y ^2 ) - 1) by XREAL_1: 13;

      (( - 1) + (y ^2 )) < ( 0 + (y ^2 )) by XREAL_1: 8;

      then ( sqrt ((y ^2 ) - 1)) < ( sqrt (y ^2 )) by A2, SQUARE_1: 27;

      then ( sqrt ((y ^2 ) - 1)) < y by A1, SQUARE_1: 22;

      then (( sqrt ((y ^2 ) - 1)) - ( sqrt ((y ^2 ) - 1))) < (y - ( sqrt ((y ^2 ) - 1))) by XREAL_1: 14;

      hence thesis;

    end;

    theorem :: SIN_COS7:26

    

     Th26: 1 <= x & 1 <= y & |.y.| <= |.x.| implies 0 <= ((y * ( sqrt ((x ^2 ) - 1))) - (x * ( sqrt ((y ^2 ) - 1))))

    proof

      assume that

       A1: 1 <= x and

       A2: 1 <= y and

       A3: |.y.| <= |.x.|;

      

       A4: 0 <= ((y ^2 ) - 1) by A2, Lm3;

      

       A5: ( |.x.| ^2 ) = (x ^2 ) & ( |.y.| ^2 ) = (y ^2 ) by COMPLEX1: 75;

      1 <= |.y.| by A2, ABSVALUE:def 1;

      then (y ^2 ) <= (x ^2 ) by A3, A5, SQUARE_1: 15;

      then (( - 1) * (x ^2 )) <= (( - 1) * (y ^2 )) by XREAL_1: 65;

      then (( - (x ^2 )) + ((x ^2 ) * (y ^2 ))) <= (( - (y ^2 )) + ((x ^2 ) * (y ^2 ))) by XREAL_1: 6;

      then 0 <= (x ^2 ) & ( sqrt ((x ^2 ) * ((y ^2 ) - 1))) <= ( sqrt ((y ^2 ) * ((x ^2 ) - 1))) by A1, A4, SQUARE_1: 26;

      then (( sqrt (x ^2 )) * ( sqrt ((y ^2 ) - 1))) <= ( sqrt ((y ^2 ) * ((x ^2 ) - 1))) by A4, SQUARE_1: 29;

      then

       A6: (x * ( sqrt ((y ^2 ) - 1))) <= ( sqrt ((y ^2 ) * ((x ^2 ) - 1))) by A1, SQUARE_1: 22;

       0 <= (y ^2 ) & 0 <= ((x ^2 ) - 1) by A1, Lm3, XREAL_1: 63;

      then (x * ( sqrt ((y ^2 ) - 1))) <= (( sqrt (y ^2 )) * ( sqrt ((x ^2 ) - 1))) by A6, SQUARE_1: 29;

      then (x * ( sqrt ((y ^2 ) - 1))) <= (y * ( sqrt ((x ^2 ) - 1))) by A2, SQUARE_1: 22;

      then ((x * ( sqrt ((y ^2 ) - 1))) - (x * ( sqrt ((y ^2 ) - 1)))) <= ((y * ( sqrt ((x ^2 ) - 1))) - (x * ( sqrt ((y ^2 ) - 1)))) by XREAL_1: 13;

      hence thesis;

    end;

    theorem :: SIN_COS7:27

    

     Th27: (x ^2 ) < 1 & (y ^2 ) < 1 implies (x * y) <> ( - 1)

    proof

      assume

       A1: (x ^2 ) < 1 & (y ^2 ) < 1;

      assume (x * y) = ( - 1);

      then ((x * y) * (x * y)) = 1;

      then ((x * x) * (y * y)) = 1;

      hence contradiction by A1, Lm2;

    end;

    theorem :: SIN_COS7:28

    

     Th28: (x ^2 ) < 1 & (y ^2 ) < 1 implies (x * y) <> 1

    proof

      assume

       A1: (x ^2 ) < 1 & (y ^2 ) < 1;

      assume (x * y) = 1;

      then ((x * y) * (x * y)) = 1;

      then ((x * x) * (y * y)) = 1;

      hence contradiction by A1, Lm2;

    end;

    theorem :: SIN_COS7:29

    

     Th29: x <> 0 implies ( exp_R x) <> 1

    proof

      assume

       A1: x <> 0 ;

      assume

       A2: ( exp_R x) = 1;

      x = ( log ( number_e ,( exp_R x))) by TAYLOR_1: 12

      .= 0 by A2, Lm1, POWER: 51, TAYLOR_1: 11;

      hence contradiction by A1;

    end;

    theorem :: SIN_COS7:30

    

     Th30: 0 <> x implies ((( exp_R x) ^2 ) - 1) <> 0

    proof

      assume

       A1: 0 <> x;

      assume ((( exp_R x) ^2 ) - 1) = 0 ;

      then ( exp_R x) = 1 or ( exp_R x) = ( - 1) by XCMPLX_1: 182;

      hence contradiction by A1, Th29, SIN_COS: 55;

    end;

    

     Lm6: ((x ^2 ) + 1) > 0

    proof

      (x ^2 ) >= 0 by XREAL_1: 63;

      hence thesis;

    end;

    theorem :: SIN_COS7:31

    

     Th31: (((t ^2 ) - 1) / ((t ^2 ) + 1)) < 1

    proof

      

       A1: 0 < ((t ^2 ) + 1) by Lm6;

      (( - 1) + (t ^2 )) < (1 + (t ^2 )) by XREAL_1: 8;

      then ((( - 1) + (t ^2 )) / (1 + (t ^2 ))) < ((1 + (t ^2 )) / (1 + (t ^2 ))) by A1, XREAL_1: 74;

      hence thesis by A1, XCMPLX_1: 60;

    end;

    theorem :: SIN_COS7:32

    

     Th32: ( - 1) < t & t < 1 implies 0 < ((t + 1) / (1 - t))

    proof

      assume ( - 1) < t & t < 1;

      then (( - 1) + 1) < (t + 1) & (t - t) < (1 - t) by XREAL_1: 8;

      then ( 0 / (1 - t)) < ((t + 1) / (1 - t));

      hence thesis;

    end;

    

     Lm7: 1 < t or t < ( - 1) implies 0 < ((t + 1) / (t - 1))

    proof

      assume

       A1: 1 < t or t < ( - 1);

      per cases by A1;

        suppose

         A2: 1 < t;

        then (1 - 1) < (t - 1) by XREAL_1: 14;

        then ( 0 / (t - 1)) < ((t + 1) / (t - 1)) by A2;

        hence thesis;

      end;

        suppose

         A3: t < ( - 1);

        then (t + 1) < (( - 1) + 1) by XREAL_1: 8;

        then ( 0 / (t - 1)) < ((t + 1) / (t - 1)) by A3;

        hence thesis;

      end;

    end;

    

     Lm8: ( sqrt ((x ^2 ) + 1)) > x

    proof

      per cases ;

        suppose

         A1: x >= 0 ;

        ((x ^2 ) + 1) > ((x ^2 ) + 0 ) by XREAL_1: 8;

        then ( sqrt ((x ^2 ) + 1)) > ( sqrt (x ^2 )) by SQUARE_1: 27, XREAL_1: 63;

        hence thesis by A1, SQUARE_1: 22;

      end;

        suppose x < 0 ;

        hence thesis by Th4;

      end;

    end;

    

     Lm9: ((( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))) - (x * y)) > 0

    proof

      

       A1: ((y ^2 ) + 1) > 0 by Lm6;

      assume ((( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))) - (x * y)) <= 0 ;

      then

       A2: (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))) <= (x * y) by XREAL_1: 50;

      ( sqrt ((x ^2 ) + 1)) > 0 & ( sqrt ((y ^2 ) + 1)) > 0 by Th4;

      then ((( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))) ^2 ) <= ((x * y) ^2 ) by A2, SQUARE_1: 15;

      then

       A3: ((( sqrt ((x ^2 ) + 1)) ^2 ) * (( sqrt ((y ^2 ) + 1)) ^2 )) <= ((x * y) ^2 );

      ((x ^2 ) + 1) > 0 by Lm6;

      then (((x ^2 ) + 1) * (( sqrt ((y ^2 ) + 1)) ^2 )) <= ((x * y) ^2 ) by A3, SQUARE_1:def 2;

      then (((x ^2 ) + 1) * ((y ^2 ) + 1)) <= ((x * y) ^2 ) by A1, SQUARE_1:def 2;

      then

       A4: ((((((x * y) ^2 ) + (x ^2 )) + (y ^2 )) + 1) - ((x * y) ^2 )) <= (((x * y) ^2 ) - ((x * y) ^2 )) by XREAL_1: 13;

       0 <= (x ^2 ) & 0 <= (y ^2 ) by XREAL_1: 63;

      then ( 0 + 1) <= (((x ^2 ) + (y ^2 )) + 1) by XREAL_1: 6;

      hence contradiction by A4;

    end;

    

     Lm10: 1 <= y implies (y + ( sqrt ((y ^2 ) - 1))) > 0

    proof

      assume

       A1: 1 <= y;

      then 0 <= ((y ^2 ) - 1) by Lm3;

      then 0 <= ( sqrt ((y ^2 ) - 1)) by SQUARE_1:def 2;

      hence thesis by A1;

    end;

    

     Lm11: 0 < t implies ( - 1) < (((t ^2 ) - 1) / ((t ^2 ) + 1))

    proof

      

       A1: 0 < ((t ^2 ) + 1) by Lm6;

      assume 0 < t;

      then 0 < (t ^2 );

      then ( 0 * 2) < (2 * (t ^2 ));

      then ( 0 - ((t ^2 ) + 1)) < ((2 * (t ^2 )) - ((t ^2 ) + 1)) by XREAL_1: 14;

      then (( - ((t ^2 ) + 1)) / ((t ^2 ) + 1)) < (((t ^2 ) - 1) / ((t ^2 ) + 1)) by A1, XREAL_1: 74;

      then ( - (((t ^2 ) + 1) / ((t ^2 ) + 1))) < (((t ^2 ) - 1) / ((t ^2 ) + 1));

      hence thesis by A1, XCMPLX_1: 60;

    end;

    

     Lm12: 0 < t & t <> 1 implies 1 < (((t ^2 ) + 1) / ((t ^2 ) - 1)) or (((t ^2 ) + 1) / ((t ^2 ) - 1)) < ( - 1)

    proof

      assume that

       A1: 0 < t and

       A2: t <> 1;

      1 < t or t < 1 by A2, XXREAL_0: 1;

      then

       A3: (1 - 1) < (t - 1) or (t - 1) < (1 - 1) by XREAL_1: 14;

      per cases by A3;

        suppose 0 < (t - 1);

        then

         A4: ( 0 + 1) < ((t - 1) + 1) by XREAL_1: 8;

        then t < (t ^2 ) by SQUARE_1: 14;

        then 1 < (t ^2 ) by A4, XXREAL_0: 2;

        then

         A5: (1 - 1) < ((t ^2 ) - 1) by XREAL_1: 14;

        (( - 1) + (t ^2 )) < (1 + (t ^2 )) by XREAL_1: 8;

        hence thesis by A5, XREAL_1: 187;

      end;

        suppose (t - 1) < 0 ;

        then

         A6: ((t - 1) + 1) < ( 0 + 1) by XREAL_1: 8;

        then (t ^2 ) < t by A1, SQUARE_1: 13;

        then (t ^2 ) < 1 by A6, XXREAL_0: 2;

        then

         A7: ((t ^2 ) - (t ^2 )) < (1 - (t ^2 )) by XREAL_1: 14;

         0 < (t ^2 ) by A1;

        then (( - (t ^2 )) + 1) < ((t ^2 ) + 1) by XREAL_1: 8;

        then 1 < (((t ^2 ) + 1) / (1 - (t ^2 ))) by A7, XREAL_1: 187;

        then (( - 1) * (((t ^2 ) + 1) / (1 - (t ^2 )))) < (1 * ( - 1)) by XREAL_1: 69;

        then (( - ((t ^2 ) + 1)) / (1 - (t ^2 ))) < (1 * ( - 1));

        then (((t ^2 ) + 1) / ( - (1 - (t ^2 )))) < (1 * ( - 1)) by XCMPLX_1: 192;

        hence thesis;

      end;

    end;

    

     Lm13: 0 < t implies 0 < ((2 * t) / (1 + (t ^2 )));

    

     Lm14: 0 < t implies ((2 * t) / (1 + (t ^2 ))) <= 1

    proof

       0 <= ((t - 1) ^2 ) by XREAL_1: 63;

      then

       A1: ( 0 + (2 * t)) <= ((((t ^2 ) - (2 * t)) + 1) + (2 * t)) by XREAL_1: 6;

      assume 0 < t;

      hence thesis by A1, XREAL_1: 183;

    end;

    

     Lm15: 0 < t implies ((1 - ( sqrt (1 + (t ^2 )))) / t) < 0

    proof

      assume

       A1: 0 < t;

      then ( 0 + 1) < ((t ^2 ) + 1) by XREAL_1: 8;

      then 1 < ( sqrt ((t ^2 ) + 1)) by SQUARE_1: 18, SQUARE_1: 27;

      then ( - ( sqrt ((t ^2 ) + 1))) < ( - 1) by XREAL_1: 24;

      then (( - ( sqrt ((t ^2 ) + 1))) + 1) < (( - 1) + 1) by XREAL_1: 8;

      then ((1 - ( sqrt ((t ^2 ) + 1))) / t) < ( 0 / t) by A1;

      hence thesis;

    end;

    

     Lm16: 0 < t & t <= 1 implies 0 <= (1 - (t ^2 ))

    proof

      assume 0 < t & t <= 1;

      then (t ^2 ) <= (1 ^2 ) by SQUARE_1: 15;

      then ((t ^2 ) - (t ^2 )) <= (1 - (t ^2 )) by XREAL_1: 13;

      hence thesis;

    end;

    

     Lm17: 0 < t & t <= 1 implies 0 <= (4 - (4 * (t ^2 )))

    proof

      assume 0 < t & t <= 1;

      then 0 <= (1 - (t ^2 )) by Lm16;

      then ( 0 * 4) <= (4 * (1 - (t ^2 )));

      hence thesis;

    end;

    

     Lm18: 0 < t & t <= 1 implies 0 < (1 + ( sqrt (1 - (t ^2 ))))

    proof

      assume 0 < t & t <= 1;

      then 0 <= (1 - (t ^2 )) by Lm16;

      then 0 <= ( sqrt (1 - (t ^2 ))) by SQUARE_1: 17, SQUARE_1: 26;

      hence thesis;

    end;

    

     Lm19: 0 < t & t <= 1 implies 0 < ((1 + ( sqrt (1 - (t ^2 )))) / t)

    proof

      assume that

       A1: 0 < t and

       A2: t <= 1;

       0 < (1 + ( sqrt (1 - (t ^2 )))) by A1, A2, Lm18;

      then ( 0 / t) < ((1 + ( sqrt (1 - (t ^2 )))) / t) by A1;

      hence thesis;

    end;

    

     Lm20: 0 < t & t <> 1 implies ((2 * t) / ((t ^2 ) - 1)) <> 0

    proof

      assume that

       A1: 0 < t and

       A2: t <> 1;

      per cases by A2, XXREAL_0: 1;

        suppose

         A3: 1 < t;

        then t < (t ^2 ) by SQUARE_1: 14;

        then 1 < (t ^2 ) by A3, XXREAL_0: 2;

        then

         A4: (1 - 1) < ((t ^2 ) - 1) by XREAL_1: 14;

        (2 * 1) < (2 * t) by A3, XREAL_1: 68;

        then ( 0 / ((t ^2 ) - 1)) < ((2 * t) / ((t ^2 ) - 1)) by A4;

        hence thesis;

      end;

        suppose

         A5: t < 1;

        then (t ^2 ) < t by A1, SQUARE_1: 13;

        then (t ^2 ) < 1 by A5, XXREAL_0: 2;

        then

         A6: ((t ^2 ) - 1) < (1 - 1) by XREAL_1: 14;

        ( 0 * 2) < (2 * t) by A1;

        then ((2 * t) / ((t ^2 ) - 1)) < ( 0 / ((t ^2 ) - 1)) by A6;

        hence thesis;

      end;

    end;

    

     Lm21: t < 0 implies ((1 + ( sqrt (1 + (t ^2 )))) / t) < 0

    proof

      assume

       A1: t < 0 ;

      ( 0 + 1) < (( sqrt (1 + (t ^2 ))) + 1) by Th4, XREAL_1: 8;

      then ((1 + ( sqrt (1 + (t ^2 )))) / t) < ( 0 / t) by A1;

      hence thesis;

    end;

    begin

    definition

      let x be Real;

      :: SIN_COS7:def1

      func sinh" (x) -> Real equals ( log ( number_e ,(x + ( sqrt ((x ^2 ) + 1)))));

      coherence ;

    end

    definition

      let x be Real;

      :: SIN_COS7:def2

      func cosh1" (x) -> Real equals ( log ( number_e ,(x + ( sqrt ((x ^2 ) - 1)))));

      coherence ;

    end

    definition

      let x be Real;

      :: SIN_COS7:def3

      func cosh2" (x) -> Real equals ( - ( log ( number_e ,(x + ( sqrt ((x ^2 ) - 1))))));

      coherence ;

    end

    definition

      let x be Real;

      :: SIN_COS7:def4

      func tanh" (x) -> Real equals ((1 / 2) * ( log ( number_e ,((1 + x) / (1 - x)))));

      coherence ;

    end

    definition

      let x be Real;

      :: SIN_COS7:def5

      func coth" (x) -> Real equals ((1 / 2) * ( log ( number_e ,((x + 1) / (x - 1)))));

      coherence ;

    end

    definition

      let x be Real;

      :: SIN_COS7:def6

      func sech1" (x) -> Real equals ( log ( number_e ,((1 + ( sqrt (1 - (x ^2 )))) / x)));

      coherence ;

    end

    definition

      let x be Real;

      :: SIN_COS7:def7

      func sech2" (x) -> Real equals ( - ( log ( number_e ,((1 + ( sqrt (1 - (x ^2 )))) / x))));

      coherence ;

    end

    definition

      let x be Real;

      :: SIN_COS7:def8

      func csch" (x) -> Real equals

      : Def8: ( log ( number_e ,((1 + ( sqrt (1 + (x ^2 )))) / x))) if 0 < x,

( log ( number_e ,((1 - ( sqrt (1 + (x ^2 )))) / x))) if x < 0 ;

      correctness ;

    end

    theorem :: SIN_COS7:33

     0 <= x implies ( sinh" x) = ( cosh1" ( sqrt ((x ^2 ) + 1)))

    proof

      assume

       A1: 0 <= x;

      (x ^2 ) >= 0 by XREAL_1: 63;

      

      then ( cosh1" ( sqrt ((x ^2 ) + 1))) = ( log ( number_e ,(( sqrt ((x ^2 ) + 1)) + ( sqrt (((x ^2 ) + 1) - 1))))) by SQUARE_1:def 2

      .= ( log ( number_e ,(( sqrt ((x ^2 ) + 1)) + x))) by A1, SQUARE_1: 22;

      hence thesis;

    end;

    theorem :: SIN_COS7:34

    x < 0 implies ( sinh" x) = ( cosh2" ( sqrt ((x ^2 ) + 1)))

    proof

      assume

       A1: x < 0 ;

      

       A2: (( sqrt ((x ^2 ) + 1)) + x) > 0 by Th5;

      

       A3: (1 / (( sqrt ((x ^2 ) + 1)) + x)) = ((( sqrt ((x ^2 ) + 1)) + x) to_power ( - 1)) by Th1, Th5;

      

       A4: (x ^2 ) >= 0 by XREAL_1: 63;

      

      then ( cosh2" ( sqrt ((x ^2 ) + 1))) = ( - ( log ( number_e ,(( sqrt ((x ^2 ) + 1)) + ( sqrt (((x ^2 ) + 1) - 1)))))) by SQUARE_1:def 2

      .= ( - ( log ( number_e ,(( sqrt ((x ^2 ) + 1)) + ( - x))))) by A1, SQUARE_1: 23

      .= ( - ( log ( number_e ,(((( sqrt ((x ^2 ) + 1)) - x) * (( sqrt ((x ^2 ) + 1)) + x)) / (( sqrt ((x ^2 ) + 1)) + x))))) by A2, XCMPLX_1: 89

      .= ( - ( log ( number_e ,(((( sqrt ((x ^2 ) + 1)) ^2 ) - (x ^2 )) / (( sqrt ((x ^2 ) + 1)) + x)))))

      .= ( - ( log ( number_e ,((((x ^2 ) + 1) - (x ^2 )) / (( sqrt ((x ^2 ) + 1)) + x))))) by A4, SQUARE_1:def 2

      .= ( - (( - 1) * ( log ( number_e ,(( sqrt ((x ^2 ) + 1)) + x))))) by A2, A3, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( log ( number_e ,(( sqrt ((x ^2 ) + 1)) + x)));

      hence thesis;

    end;

    theorem :: SIN_COS7:35

    ( sinh" x) = ( tanh" (x / ( sqrt ((x ^2 ) + 1))))

    proof

      set t = (( sqrt ((x ^2 ) + 1)) + x);

      

       A1: (( sqrt ((x ^2 ) + 1)) + x) > 0 by Th5;

      

       A2: ((x ^2 ) + 1) > 0 by Lm6;

      

       A3: ( sqrt ((x ^2 ) + 1)) > 0 by Th4;

      

      then ( tanh" (x / ( sqrt ((x ^2 ) + 1)))) = ((1 / 2) * ( log ( number_e ,((((( sqrt ((x ^2 ) + 1)) * 1) + x) / ( sqrt ((x ^2 ) + 1))) / (1 - (x / ( sqrt ((x ^2 ) + 1)))))))) by XCMPLX_1: 113

      .= ((1 / 2) * ( log ( number_e ,((((( sqrt ((x ^2 ) + 1)) * 1) + x) / ( sqrt ((x ^2 ) + 1))) / (((1 * ( sqrt ((x ^2 ) + 1))) - x) / ( sqrt ((x ^2 ) + 1))))))) by A3, XCMPLX_1: 127

      .= ((1 / 2) * ( log ( number_e ,(t / (( sqrt ((x ^2 ) + 1)) - x))))) by A3, XCMPLX_1: 55

      .= ((1 / 2) * ( log ( number_e ,((t * t) / ((( sqrt ((x ^2 ) + 1)) - x) * t))))) by A1, XCMPLX_1: 91

      .= ((1 / 2) * ( log ( number_e ,((t * t) / ((( sqrt ((x ^2 ) + 1)) * ( sqrt ((x ^2 ) + 1))) - (x ^2 ))))))

      .= ((1 / 2) * ( log ( number_e ,((t * t) / (( sqrt (((x ^2 ) + 1) ^2 )) - (x ^2 )))))) by A2, SQUARE_1: 29

      .= ((1 / 2) * ( log ( number_e ,((t * t) / (((x ^2 ) + 1) - (x ^2 )))))) by A2, SQUARE_1: 22

      .= ((1 / 2) * ( log ( number_e ,(t ^2 ))))

      .= ((1 / 2) * ( log ( number_e ,(t to_power 2)))) by POWER: 46

      .= ((1 / 2) * (2 * ( log ( number_e ,t)))) by A1, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( log ( number_e ,t));

      hence thesis;

    end;

    theorem :: SIN_COS7:36

    x >= 1 implies ( cosh1" x) = ( sinh" ( sqrt ((x ^2 ) - 1)))

    proof

      assume

       A1: x >= 1;

      then ((x ^2 ) - 1) >= 0 by Lm3;

      

      then ( sinh" ( sqrt ((x ^2 ) - 1))) = ( log ( number_e ,(( sqrt ((x ^2 ) - 1)) + ( sqrt (((x ^2 ) - 1) + 1))))) by SQUARE_1:def 2

      .= ( log ( number_e ,(( sqrt ((x ^2 ) - 1)) + x))) by A1, SQUARE_1: 22;

      hence thesis;

    end;

    theorem :: SIN_COS7:37

    x > 1 implies ( cosh1" x) = ( tanh" (( sqrt ((x ^2 ) - 1)) / x))

    proof

      assume

       A1: x > 1;

      then

       A2: (( sqrt ((x ^2 ) - 1)) + x) > 0 by Th23;

      (x ^2 ) > ((1 ^2 ) + 0 ) by A1, SQUARE_1: 16;

      then

       A3: ((x ^2 ) - 1) > 0 by XREAL_1: 20;

      ( tanh" (( sqrt ((x ^2 ) - 1)) / x)) = ((1 / 2) * ( log ( number_e ,(((( sqrt ((x ^2 ) - 1)) + (x * 1)) / x) / (1 - (( sqrt ((x ^2 ) - 1)) / x)))))) by A1, XCMPLX_1: 113

      .= ((1 / 2) * ( log ( number_e ,(((( sqrt ((x ^2 ) - 1)) + x) / x) / (((1 * x) - ( sqrt ((x ^2 ) - 1))) / x))))) by A1, XCMPLX_1: 127

      .= ((1 / 2) * ( log ( number_e ,((( sqrt ((x ^2 ) - 1)) + x) / (x - ( sqrt ((x ^2 ) - 1))))))) by A1, XCMPLX_1: 55

      .= ((1 / 2) * ( log ( number_e ,(((( sqrt ((x ^2 ) - 1)) + x) * (( sqrt ((x ^2 ) - 1)) + x)) / ((x - ( sqrt ((x ^2 ) - 1))) * (( sqrt ((x ^2 ) - 1)) + x)))))) by A2, XCMPLX_1: 91

      .= ((1 / 2) * ( log ( number_e ,(((( sqrt ((x ^2 ) - 1)) + x) * (( sqrt ((x ^2 ) - 1)) + x)) / ((x ^2 ) - (( sqrt ((x ^2 ) - 1)) ^2 ))))))

      .= ((1 / 2) * ( log ( number_e ,(((( sqrt ((x ^2 ) - 1)) + x) * (( sqrt ((x ^2 ) - 1)) + x)) / ((x ^2 ) - ((x ^2 ) - 1)))))) by A3, SQUARE_1:def 2

      .= ((1 / 2) * ( log ( number_e ,((( sqrt ((x ^2 ) - 1)) + x) ^2 ))))

      .= ((1 / 2) * ( log ( number_e ,((( sqrt ((x ^2 ) - 1)) + x) to_power 2)))) by POWER: 46

      .= ((1 / 2) * (2 * ( log ( number_e ,(( sqrt ((x ^2 ) - 1)) + x))))) by A2, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( log ( number_e ,(( sqrt ((x ^2 ) - 1)) + x)));

      hence thesis;

    end;

    theorem :: SIN_COS7:38

    x >= 1 implies ( cosh1" x) = (2 * ( cosh1" ( sqrt ((x + 1) / 2))))

    proof

      assume

       A1: x >= 1;

      then

       A2: ((x - 1) / 2) >= 0 by Th7;

      

       A3: (((x ^2 ) - 1) / 4) >= 0 by A1, Th9;

      

       A4: (( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) > 0 by A1, Th10;

      (2 * ( cosh1" ( sqrt ((x + 1) / 2)))) = (2 * ( log ( number_e ,(( sqrt ((x + 1) / 2)) + ( sqrt (((x + 1) / 2) - 1)))))) by A1, SQUARE_1:def 2

      .= ( log ( number_e ,((( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) to_power 2))) by A4, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( log ( number_e ,((( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) ^2 ))) by POWER: 46

      .= ( log ( number_e ,(((( sqrt ((x + 1) / 2)) ^2 ) + ((2 * ( sqrt ((x + 1) / 2))) * ( sqrt ((x - 1) / 2)))) + (( sqrt ((x - 1) / 2)) ^2 ))))

      .= ( log ( number_e ,((((x + 1) / 2) + ((2 * ( sqrt ((x + 1) / 2))) * ( sqrt ((x - 1) / 2)))) + (( sqrt ((x - 1) / 2)) ^2 )))) by A1, SQUARE_1:def 2

      .= ( log ( number_e ,((((x + 1) / 2) + ((2 * ( sqrt ((x + 1) / 2))) * ( sqrt ((x - 1) / 2)))) + ((x - 1) / 2)))) by A2, SQUARE_1:def 2

      .= ( log ( number_e ,(x + (2 * (( sqrt ((x + 1) / 2)) * ( sqrt ((x - 1) / 2)))))))

      .= ( log ( number_e ,(x + (2 * ( sqrt (((x + 1) / 2) * ((x - 1) / 2))))))) by A1, A2, SQUARE_1: 29

      .= ( log ( number_e ,(x + (( sqrt (2 ^2 )) * ( sqrt (((x ^2 ) - 1) / 4)))))) by SQUARE_1: 22

      .= ( log ( number_e ,(x + ( sqrt (4 * (((x ^2 ) - 1) / 4)))))) by A3, SQUARE_1: 29

      .= ( log ( number_e ,(x + ( sqrt ((x ^2 ) - 1)))));

      hence thesis;

    end;

    theorem :: SIN_COS7:39

    x >= 1 implies ( cosh2" x) = (2 * ( cosh2" ( sqrt ((x + 1) / 2))))

    proof

      assume

       A1: x >= 1;

      then

       A2: ((x - 1) / 2) >= 0 by Th7;

      

       A3: (((x ^2 ) - 1) / 4) >= 0 by A1, Th9;

      

       A4: (( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) > 0 by A1, Th10;

      (2 * ( cosh2" ( sqrt ((x + 1) / 2)))) = (2 * ( - ( log ( number_e ,(( sqrt ((x + 1) / 2)) + ( sqrt (((x + 1) / 2) - 1))))))) by A1, SQUARE_1:def 2

      .= ( - (2 * ( log ( number_e ,(( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2)))))))

      .= ( - ( log ( number_e ,((( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) to_power 2)))) by A4, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( - ( log ( number_e ,((( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) ^2 )))) by POWER: 46

      .= ( - ( log ( number_e ,(((( sqrt ((x + 1) / 2)) ^2 ) + ((2 * ( sqrt ((x + 1) / 2))) * ( sqrt ((x - 1) / 2)))) + (( sqrt ((x - 1) / 2)) ^2 )))))

      .= ( - ( log ( number_e ,((((x + 1) / 2) + ((2 * ( sqrt ((x + 1) / 2))) * ( sqrt ((x - 1) / 2)))) + (( sqrt ((x - 1) / 2)) ^2 ))))) by A1, SQUARE_1:def 2

      .= ( - ( log ( number_e ,((((x + 1) / 2) + ((2 * ( sqrt ((x + 1) / 2))) * ( sqrt ((x - 1) / 2)))) + ((x - 1) / 2))))) by A2, SQUARE_1:def 2

      .= ( - ( log ( number_e ,(x + (2 * (( sqrt ((x + 1) / 2)) * ( sqrt ((x - 1) / 2))))))))

      .= ( - ( log ( number_e ,(x + (2 * ( sqrt (((x + 1) / 2) * ((x - 1) / 2)))))))) by A1, A2, SQUARE_1: 29

      .= ( - ( log ( number_e ,(x + (( sqrt (2 ^2 )) * ( sqrt (((x ^2 ) - 1) / 4))))))) by SQUARE_1: 22

      .= ( - ( log ( number_e ,(x + ( sqrt (4 * (((x ^2 ) - 1) / 4))))))) by A3, SQUARE_1: 29

      .= ( - ( log ( number_e ,(x + ( sqrt ((x ^2 ) - 1))))));

      hence thesis;

    end;

    theorem :: SIN_COS7:40

    x >= 1 implies ( cosh1" x) = (2 * ( sinh" ( sqrt ((x - 1) / 2))))

    proof

      assume

       A1: x >= 1;

      then

       A2: (( sqrt ((x + 1) / 2)) + ( sqrt ((x - 1) / 2))) > 0 by Th10;

      

       A3: (((x ^2 ) - 1) / 4) >= 0 by A1, Th9;

      

       A4: ((x - 1) / 2) >= 0 by A1, Th7;

      

      then (2 * ( sinh" ( sqrt ((x - 1) / 2)))) = (2 * ( log ( number_e ,(( sqrt ((x - 1) / 2)) + ( sqrt (((x - 1) / 2) + 1)))))) by SQUARE_1:def 2

      .= ( log ( number_e ,((( sqrt ((x - 1) / 2)) + ( sqrt ((x + 1) / 2))) to_power 2))) by A2, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( log ( number_e ,((( sqrt ((x - 1) / 2)) + ( sqrt ((x + 1) / 2))) ^2 ))) by POWER: 46

      .= ( log ( number_e ,(((( sqrt ((x - 1) / 2)) ^2 ) + ((2 * ( sqrt ((x - 1) / 2))) * ( sqrt ((x + 1) / 2)))) + (( sqrt ((x + 1) / 2)) ^2 ))))

      .= ( log ( number_e ,((((x - 1) / 2) + ((2 * ( sqrt ((x - 1) / 2))) * ( sqrt ((x + 1) / 2)))) + (( sqrt ((x + 1) / 2)) ^2 )))) by A4, SQUARE_1:def 2

      .= ( log ( number_e ,((((x - 1) / 2) + ((2 * ( sqrt ((x - 1) / 2))) * ( sqrt ((x + 1) / 2)))) + ((x + 1) / 2)))) by A1, SQUARE_1:def 2

      .= ( log ( number_e ,(x + (2 * (( sqrt ((x - 1) / 2)) * ( sqrt ((x + 1) / 2)))))))

      .= ( log ( number_e ,(x + (2 * ( sqrt (((x - 1) / 2) * ((x + 1) / 2))))))) by A1, A4, SQUARE_1: 29

      .= ( log ( number_e ,(x + (( sqrt (2 ^2 )) * ( sqrt (((x ^2 ) - 1) / 4)))))) by SQUARE_1: 22

      .= ( log ( number_e ,(x + ( sqrt (4 * (((x ^2 ) - 1) / 4)))))) by A3, SQUARE_1: 29

      .= ( log ( number_e ,(x + ( sqrt ((x ^2 ) - 1)))));

      hence thesis;

    end;

    theorem :: SIN_COS7:41

    (x ^2 ) < 1 implies ( tanh" x) = ( sinh" (x / ( sqrt (1 - (x ^2 )))))

    proof

      assume

       A1: (x ^2 ) < 1;

      then

       A2: (x + 1) > 0 by Th11;

      

       A3: ( sqrt (x + 1)) > 0 by A1, Th11, SQUARE_1: 25;

      

       A4: ((x + 1) / (1 - x)) > 0 by A1, Lm4;

      

       A5: (1 - (x ^2 )) > 0 by A1, XREAL_1: 50;

      

       A6: (1 - x) > 0 by A1, Th11;

      then

       A7: ( sqrt ((x + 1) / (1 - x))) = (((x + 1) / (1 - x)) to_power (1 / 2)) by A2, ASYMPT_1: 83;

      ( sinh" (x / ( sqrt (1 - (x ^2 ))))) = ( log ( number_e ,((x / ( sqrt (1 - (x ^2 )))) + ( sqrt (((x ^2 ) / (( sqrt (1 - (x ^2 ))) ^2 )) + 1))))) by XCMPLX_1: 76

      .= ( log ( number_e ,((x / ( sqrt (1 - (x ^2 )))) + ( sqrt (((x ^2 ) / (1 - (x ^2 ))) + 1))))) by A5, SQUARE_1:def 2

      .= ( log ( number_e ,((x / ( sqrt (1 - (x ^2 )))) + ( sqrt (((x ^2 ) + ((1 - (x ^2 )) * 1)) / (1 - (x ^2 ))))))) by A5, XCMPLX_1: 113

      .= ( log ( number_e ,((x / ( sqrt (1 - (x ^2 )))) + (( sqrt 1) / ( sqrt (1 - (x ^2 ))))))) by A5, SQUARE_1: 30

      .= ( log ( number_e ,((x + 1) / ( sqrt ((1 - x) * (1 + x)))))) by SQUARE_1: 18

      .= ( log ( number_e ,(( sqrt ((x + 1) ^2 )) / ( sqrt ((1 - x) * (1 + x)))))) by A2, SQUARE_1: 22

      .= ( log ( number_e ,((( sqrt (x + 1)) * ( sqrt (x + 1))) / ( sqrt ((1 - x) * (1 + x)))))) by A2, SQUARE_1: 29

      .= ( log ( number_e ,((( sqrt (x + 1)) * ( sqrt (x + 1))) / (( sqrt (1 - x)) * ( sqrt (1 + x)))))) by A2, A6, SQUARE_1: 29

      .= ( log ( number_e ,(( sqrt (x + 1)) / ( sqrt (1 - x))))) by A3, XCMPLX_1: 91

      .= ( log ( number_e ,( sqrt ((x + 1) / (1 - x))))) by A2, A6, SQUARE_1: 30

      .= ((1 / 2) * ( log ( number_e ,((1 + x) / (1 - x))))) by A4, A7, Lm1, POWER: 55, TAYLOR_1: 11;

      hence thesis;

    end;

    theorem :: SIN_COS7:42

     0 < x & x < 1 implies ( tanh" x) = ( cosh1" (1 / ( sqrt (1 - (x ^2 )))))

    proof

      assume that

       A1: 0 < x and

       A2: x < 1;

      

       A3: (1 - (x ^2 )) > 0 by A1, A2, Lm5;

      

       A4: ((1 + x) / (1 - x)) > 0 by A1, A2, Th15;

      

       A5: (1 - x) > 0 by A2, XREAL_1: 50;

      

       A6: ( sqrt (1 + x)) > 0 by A1, SQUARE_1: 25;

      ((1 + x) / (1 - x)) > 0 by A1, A2, Th15;

      then

       A7: ( sqrt ((1 + x) / (1 - x))) = (((1 + x) / (1 - x)) to_power (1 / 2)) by ASYMPT_1: 83;

      

       A8: (x ^2 ) >= 0 by XREAL_1: 63;

      ( cosh1" (1 / ( sqrt (1 - (x ^2 ))))) = ( log ( number_e ,((1 / ( sqrt (1 - (x ^2 )))) + ( sqrt ((1 / (( sqrt (1 - (x ^2 ))) ^2 )) - (1 ^2 )))))) by XCMPLX_1: 76

      .= ( log ( number_e ,((1 / ( sqrt (1 - (x ^2 )))) + ( sqrt ((1 / (1 - (x ^2 ))) - 1))))) by A3, SQUARE_1:def 2

      .= ( log ( number_e ,((1 / ( sqrt (1 - (x ^2 )))) + ( sqrt ((1 - (1 * (1 - (x ^2 )))) / (1 - (x ^2 ))))))) by A3, XCMPLX_1: 126

      .= ( log ( number_e ,((1 / ( sqrt (1 - (x ^2 )))) + (( sqrt (x ^2 )) / ( sqrt (1 - (x ^2 ))))))) by A3, A8, SQUARE_1: 30

      .= ( log ( number_e ,((1 / ( sqrt (1 - (x ^2 )))) + (x / ( sqrt (1 - (x ^2 ))))))) by A1, SQUARE_1: 22

      .= ( log ( number_e ,((1 + x) / ( sqrt ((1 - x) * (1 + x))))))

      .= ( log ( number_e ,((1 + x) / (( sqrt (1 - x)) * ( sqrt (1 + x)))))) by A1, A5, SQUARE_1: 29

      .= ( log ( number_e ,(( sqrt ((1 + x) ^2 )) / (( sqrt (1 - x)) * ( sqrt (1 + x)))))) by A1, SQUARE_1: 22

      .= ( log ( number_e ,((( sqrt (1 + x)) * ( sqrt (1 + x))) / (( sqrt (1 - x)) * ( sqrt (1 + x)))))) by A1, SQUARE_1: 29

      .= ( log ( number_e ,(( sqrt (1 + x)) / ( sqrt (1 - x))))) by A6, XCMPLX_1: 91

      .= ( log ( number_e ,( sqrt ((1 + x) / (1 - x))))) by A1, A5, SQUARE_1: 30

      .= ((1 / 2) * ( log ( number_e ,((1 + x) / (1 - x))))) by A7, A4, Lm1, POWER: 55, TAYLOR_1: 11;

      hence thesis;

    end;

    theorem :: SIN_COS7:43

    (x ^2 ) < 1 implies ( tanh" x) = ((1 / 2) * ( sinh" ((2 * x) / (1 - (x ^2 )))))

    proof

      assume

       A1: (x ^2 ) < 1;

      then

       A2: ((1 - (x ^2 )) ^2 ) > 0 by Th12;

      

       A3: (x + 1) > 0 by A1, Th11;

      ((1 / 2) * ( sinh" ((2 * x) / (1 - (x ^2 ))))) = ((1 / 2) * ( log ( number_e ,(((2 * x) / (1 - (x ^2 ))) + ( sqrt ((((2 * x) ^2 ) / ((1 - (x ^2 )) ^2 )) + 1)))))) by XCMPLX_1: 76

      .= ((1 / 2) * ( log ( number_e ,(((2 * x) / (1 - (x ^2 ))) + ( sqrt (((4 * (x ^2 )) + (((1 - (x ^2 )) ^2 ) * 1)) / ((1 - (x ^2 )) ^2 ))))))) by A2, XCMPLX_1: 113

      .= ((1 / 2) * ( log ( number_e ,(((2 * x) / (1 - (x ^2 ))) + ( sqrt ((((x ^2 ) + 1) ^2 ) / ((1 - (x ^2 )) ^2 )))))))

      .= ((1 / 2) * ( log ( number_e ,(((2 * x) / (1 - (x ^2 ))) + ( sqrt ((((x ^2 ) + 1) / (1 - (x ^2 ))) ^2 )))))) by XCMPLX_1: 76

      .= ((1 / 2) * ( log ( number_e ,(((2 * x) / (1 - (x ^2 ))) + (((x ^2 ) + 1) / (1 - (x ^2 ))))))) by A1, Th13, SQUARE_1: 22

      .= ((1 / 2) * ( log ( number_e ,(((2 * x) + ((x ^2 ) + 1)) / (1 - (x ^2 ))))))

      .= ((1 / 2) * ( log ( number_e ,(((x + 1) * (x + 1)) / ((1 - x) * (1 + x))))))

      .= ((1 / 2) * ( log ( number_e ,((x + 1) / (1 - x))))) by A3, XCMPLX_1: 91;

      hence thesis;

    end;

    theorem :: SIN_COS7:44

    x > 0 & x < 1 implies ( tanh" x) = ((1 / 2) * ( cosh1" ((1 + (x ^2 )) / (1 - (x ^2 )))))

    proof

      assume that

       A1: x > 0 and

       A2: x < 1;

      

       A3: 0 < ((1 - (x ^2 )) ^2 ) by A1, A2, Th19;

      

       A4: ((2 * x) / (1 - (x ^2 ))) > 0 by A1, A2, Th18;

      ((1 / 2) * ( cosh1" ((1 + (x ^2 )) / (1 - (x ^2 ))))) = ((1 / 2) * ( log ( number_e ,(((1 + (x ^2 )) / (1 - (x ^2 ))) + ( sqrt ((((1 + (x ^2 )) ^2 ) / ((1 - (x ^2 )) ^2 )) - 1)))))) by XCMPLX_1: 76

      .= ((1 / 2) * ( log ( number_e ,(((1 + (x ^2 )) / (1 - (x ^2 ))) + ( sqrt ((((1 + (x ^2 )) ^2 ) - (1 * ((1 - (x ^2 )) ^2 ))) / ((1 - (x ^2 )) ^2 ))))))) by A3, XCMPLX_1: 126

      .= ((1 / 2) * ( log ( number_e ,(((1 + (x ^2 )) / (1 - (x ^2 ))) + ( sqrt (((2 * x) ^2 ) / ((1 - (x ^2 )) ^2 )))))))

      .= ((1 / 2) * ( log ( number_e ,(((1 + (x ^2 )) / (1 - (x ^2 ))) + ( sqrt (((2 * x) / (1 - (x ^2 ))) ^2 )))))) by XCMPLX_1: 76

      .= ((1 / 2) * ( log ( number_e ,(((1 + (x ^2 )) / (1 - (x ^2 ))) + ((2 * x) / (1 - (x ^2 ))))))) by A4, SQUARE_1: 22

      .= ((1 / 2) * ( log ( number_e ,(((1 + (x ^2 )) + (2 * x)) / (1 - (x ^2 ))))))

      .= ((1 / 2) * ( log ( number_e ,(((x + 1) * (x + 1)) / ((1 - x) * (1 + x))))))

      .= ((1 / 2) * ( log ( number_e ,((x + 1) / (1 - x))))) by A1, XCMPLX_1: 91;

      hence thesis;

    end;

    theorem :: SIN_COS7:45

    (x ^2 ) < 1 implies ( tanh" x) = ((1 / 2) * ( tanh" ((2 * x) / (1 + (x ^2 )))))

    proof

      assume (x ^2 ) < 1;

      then

       A1: ((x + 1) / (1 - x)) > 0 by Lm4;

      

       A2: (1 + (x ^2 )) > 0 by Lm6;

      

      then ((1 / 2) * ( tanh" ((2 * x) / (1 + (x ^2 ))))) = ((1 / 2) * ((1 / 2) * ( log ( number_e ,((((2 * x) + ((1 + (x ^2 )) * 1)) / (1 + (x ^2 ))) / (1 - ((2 * x) / (1 + (x ^2 ))))))))) by XCMPLX_1: 113

      .= ((1 / 2) * ((1 / 2) * ( log ( number_e ,(((((2 * x) + 1) + (x ^2 )) / (1 + (x ^2 ))) / (((1 * (1 + (x ^2 ))) - (2 * x)) / (1 + (x ^2 )))))))) by A2, XCMPLX_1: 127

      .= ((1 / 2) * ((1 / 2) * ( log ( number_e ,(((x + 1) ^2 ) / ((1 - x) ^2 )))))) by A2, XCMPLX_1: 55

      .= ((1 / 2) * ((1 / 2) * ( log ( number_e ,(((x + 1) / (1 - x)) ^2 ))))) by XCMPLX_1: 76

      .= ((1 / 2) * ((1 / 2) * ( log ( number_e ,(((x + 1) / (1 - x)) to_power 2))))) by POWER: 46

      .= ((1 / 2) * ((1 / 2) * (2 * ( log ( number_e ,((x + 1) / (1 - x))))))) by A1, Lm1, POWER: 55, TAYLOR_1: 11

      .= ((1 / 2) * ( log ( number_e ,((1 + x) / (1 - x)))));

      hence thesis;

    end;

    theorem :: SIN_COS7:46

    (x ^2 ) > 1 implies ( coth" x) = ( tanh" (1 / x))

    proof

      assume (x ^2 ) > 1;

      then

       A1: x <> 0 ;

      

      then ( tanh" (1 / x)) = ((1 / 2) * ( log ( number_e ,(((1 + (x * 1)) / x) / (1 - (1 / x)))))) by XCMPLX_1: 113

      .= ((1 / 2) * ( log ( number_e ,(((1 + (x * 1)) / x) / (((1 * x) - 1) / x))))) by A1, XCMPLX_1: 127

      .= ((1 / 2) * ( log ( number_e ,((1 + x) / (x - 1))))) by A1, XCMPLX_1: 55;

      hence thesis;

    end;

    theorem :: SIN_COS7:47

    x > 0 & x <= 1 implies ( sech1" x) = ( cosh1" (1 / x))

    proof

      assume that

       A1: x > 0 and

       A2: x <= 1;

      

       A3: (1 - (x ^2 )) >= 0 by A1, A2, Th22;

      

       A4: (x ^2 ) > 0 by A1;

      ( cosh1" (1 / x)) = ( log ( number_e ,((1 / x) + ( sqrt ((1 / (x ^2 )) - (1 ^2 )))))) by XCMPLX_1: 76

      .= ( log ( number_e ,((1 / x) + ( sqrt ((1 - (1 * (x ^2 ))) / (x ^2 )))))) by A4, XCMPLX_1: 126

      .= ( log ( number_e ,((1 / x) + (( sqrt (1 - (x ^2 ))) / ( sqrt (x ^2 )))))) by A1, A3, SQUARE_1: 30

      .= ( log ( number_e ,((1 / x) + (( sqrt (1 - (x ^2 ))) / x)))) by A1, SQUARE_1: 22

      .= ( log ( number_e ,((1 + ( sqrt (1 - (x ^2 )))) / x)));

      hence thesis;

    end;

    theorem :: SIN_COS7:48

    x > 0 & x <= 1 implies ( sech2" x) = ( cosh2" (1 / x))

    proof

      assume that

       A1: x > 0 and

       A2: x <= 1;

      

       A3: (1 - (x ^2 )) >= 0 by A1, A2, Th22;

      

       A4: (x ^2 ) > 0 by A1;

      ( cosh2" (1 / x)) = ( - ( log ( number_e ,((1 / x) + ( sqrt ((1 / (x ^2 )) - (1 ^2 ))))))) by XCMPLX_1: 76

      .= ( - ( log ( number_e ,((1 / x) + ( sqrt ((1 - (1 * (x ^2 ))) / (x ^2 ))))))) by A4, XCMPLX_1: 126

      .= ( - ( log ( number_e ,((1 / x) + (( sqrt (1 - (x ^2 ))) / ( sqrt (x ^2 ))))))) by A1, A3, SQUARE_1: 30

      .= ( - ( log ( number_e ,((1 / x) + (( sqrt (1 - (x ^2 ))) / x))))) by A1, SQUARE_1: 22

      .= ( - ( log ( number_e ,((1 + ( sqrt (1 - (x ^2 )))) / x))));

      hence thesis;

    end;

    theorem :: SIN_COS7:49

    x > 0 implies ( csch" x) = ( sinh" (1 / x))

    proof

      assume

       A1: x > 0 ;

      then

       A2: (x ^2 ) > 0 ;

      ( sinh" (1 / x)) = ( log ( number_e ,((1 / x) + ( sqrt ((1 / (x ^2 )) + (1 ^2 )))))) by XCMPLX_1: 76

      .= ( log ( number_e ,((1 / x) + ( sqrt ((1 + ((x ^2 ) * 1)) / (x ^2 )))))) by A2, XCMPLX_1: 113

      .= ( log ( number_e ,((1 / x) + (( sqrt (1 + (x ^2 ))) / ( sqrt (x ^2 )))))) by A1, SQUARE_1: 30

      .= ( log ( number_e ,((1 / x) + (( sqrt (1 + (x ^2 ))) / x)))) by A1, SQUARE_1: 22

      .= ( log ( number_e ,((1 + ( sqrt (1 + (x ^2 )))) / x)));

      hence thesis by A1, Def8;

    end;

    theorem :: SIN_COS7:50

    ((x * y) + (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) >= 0 implies (( sinh" x) + ( sinh" y)) = ( sinh" ((x * ( sqrt (1 + (y ^2 )))) + (y * ( sqrt (1 + (x ^2 ))))))

    proof

      assume

       A1: ((x * y) + (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) >= 0 ;

      (( sqrt ((x ^2 ) + 1)) + x) > 0 & (( sqrt ((y ^2 ) + 1)) + y) > 0 by Th5;

      

      then

       A2: (( sinh" x) + ( sinh" y)) = ( log ( number_e ,((x + ( sqrt ((x ^2 ) + 1))) * (y + ( sqrt ((y ^2 ) + 1)))))) by Lm1, POWER: 53, TAYLOR_1: 11

      .= ( log ( number_e ,(((x * ( sqrt ((y ^2 ) + 1))) + (( sqrt ((x ^2 ) + 1)) * y)) + ((x * y) + (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))))))

      .= ( log ( number_e ,(((x * ( sqrt ((y ^2 ) + 1))) + (( sqrt ((x ^2 ) + 1)) * y)) + ( sqrt (((x * y) + (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) ^2 ))))) by A1, SQUARE_1: 22;

      

       A3: ((y ^2 ) + 1) >= 0 by Lm6;

      set p = ( sqrt ((((x * ( sqrt (1 + (y ^2 )))) + (y * ( sqrt (1 + (x ^2 ))))) ^2 ) + 1));

      set t = ( sqrt (((x * y) + (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) ^2 ));

      

       A4: ((x ^2 ) + 1) >= 0 by Lm6;

      

       A5: p = ( sqrt (((((x ^2 ) * (( sqrt (1 + (y ^2 ))) ^2 )) + ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y * ( sqrt (1 + (x ^2 )))) ^2 )) + 1))

      .= ( sqrt (((((x ^2 ) * (1 + (y ^2 ))) + ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y * ( sqrt (1 + (x ^2 )))) ^2 )) + 1)) by A3, SQUARE_1:def 2

      .= ( sqrt (((((x ^2 ) + ((x * y) ^2 )) + ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y ^2 ) * (( sqrt (1 + (x ^2 ))) ^2 ))) + 1))

      .= ( sqrt (((((x ^2 ) + ((x * y) ^2 )) + ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y ^2 ) * (1 + (x ^2 )))) + 1)) by A4, SQUARE_1:def 2

      .= ( sqrt (((((x ^2 ) + (2 * ((x * y) ^2 ))) + (y ^2 )) + 1) + (((2 * x) * y) * (( sqrt (1 + (y ^2 ))) * ( sqrt (1 + (x ^2 )))))))

      .= ( sqrt (((((x ^2 ) + (2 * ((x * y) ^2 ))) + (y ^2 )) + 1) + (((2 * x) * y) * ( sqrt ((1 + (y ^2 )) * (1 + (x ^2 ))))))) by A4, A3, SQUARE_1: 29;

      t = ( sqrt (((x * y) + ( sqrt (((x ^2 ) + 1) * ((y ^2 ) + 1)))) ^2 )) by A4, A3, SQUARE_1: 29

      .= ( sqrt ((((x * y) ^2 ) + ((2 * (x * y)) * ( sqrt (((x ^2 ) + 1) * ((y ^2 ) + 1))))) + (( sqrt (((x ^2 ) + 1) * ((y ^2 ) + 1))) ^2 )))

      .= ( sqrt ((((x * y) ^2 ) + ((2 * (x * y)) * ( sqrt (((x ^2 ) + 1) * ((y ^2 ) + 1))))) + (((((x * y) ^2 ) + (x ^2 )) + (y ^2 )) + 1))) by A4, A3, SQUARE_1:def 2

      .= ( sqrt (((((2 * ((x * y) ^2 )) + (x ^2 )) + (y ^2 )) + 1) + ((2 * (x * y)) * ( sqrt (((x ^2 ) + 1) * ((y ^2 ) + 1))))));

      hence thesis by A2, A5;

    end;

    theorem :: SIN_COS7:51

    (( sinh" x) - ( sinh" y)) = ( sinh" ((x * ( sqrt (1 + (y ^2 )))) - (y * ( sqrt (1 + (x ^2 ))))))

    proof

      set t = ((( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))) - (x * y));

      set q = ( sqrt ((((x * ( sqrt (1 + (y ^2 )))) - (y * ( sqrt (1 + (x ^2 ))))) ^2 ) + 1));

      

       A1: ((x ^2 ) + 1) >= 0 by Lm6;

      (y + 0 ) < ( sqrt ((y ^2 ) + 1)) by Lm8;

      then

       A2: (( sqrt ((y ^2 ) + 1)) - y) > 0 by XREAL_1: 20;

      

       A3: ((y ^2 ) + 1) >= 0 by Lm6;

      ((( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))) - (x * y)) >= 0 by Lm9;

      

      then

       A4: t = ( sqrt (((( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))) - (x * y)) ^2 )) by SQUARE_1: 22

      .= ( sqrt ((((( sqrt ((x ^2 ) + 1)) ^2 ) * (( sqrt ((y ^2 ) + 1)) ^2 )) - ((2 * (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) * (x * y))) + ((x * y) ^2 )))

      .= ( sqrt (((((x ^2 ) + 1) * (( sqrt ((y ^2 ) + 1)) ^2 )) - ((2 * (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) * (x * y))) + ((x * y) ^2 ))) by A1, SQUARE_1:def 2

      .= ( sqrt (((((x ^2 ) + 1) * ((y ^2 ) + 1)) - ((2 * (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) * (x * y))) + ((x * y) ^2 ))) by A3, SQUARE_1:def 2

      .= ( sqrt (((((2 * ((x * y) ^2 )) + (x ^2 )) + (y ^2 )) + 1) - ((2 * (x * y)) * (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1))))));

      

       A5: q = ( sqrt (((((x ^2 ) * (( sqrt (1 + (y ^2 ))) ^2 )) - ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y * ( sqrt (1 + (x ^2 )))) ^2 )) + 1))

      .= ( sqrt (((((x ^2 ) * (1 + (y ^2 ))) - ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y * ( sqrt (1 + (x ^2 )))) ^2 )) + 1)) by A3, SQUARE_1:def 2

      .= ( sqrt (((((x ^2 ) + ((x ^2 ) * (y ^2 ))) - ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y ^2 ) * (( sqrt (1 + (x ^2 ))) ^2 ))) + 1))

      .= ( sqrt (((((x ^2 ) + ((x ^2 ) * (y ^2 ))) - ((2 * (x * ( sqrt (1 + (y ^2 ))))) * (y * ( sqrt (1 + (x ^2 )))))) + ((y ^2 ) * (1 + (x ^2 )))) + 1)) by A1, SQUARE_1:def 2

      .= ( sqrt (((((x ^2 ) + (y ^2 )) + (2 * ((x * y) ^2 ))) + 1) - ((((2 * x) * y) * ( sqrt (1 + (y ^2 )))) * ( sqrt (1 + (x ^2 ))))));

      (( sqrt ((x ^2 ) + 1)) + x) > 0 & (( sqrt ((y ^2 ) + 1)) + y) > 0 by Th5;

      

      then (( sinh" x) - ( sinh" y)) = ( log ( number_e ,((x + ( sqrt ((x ^2 ) + 1))) / (y + ( sqrt ((y ^2 ) + 1)))))) by Lm1, POWER: 54, TAYLOR_1: 11

      .= ( log ( number_e ,(((x + ( sqrt ((x ^2 ) + 1))) * (( sqrt ((y ^2 ) + 1)) - y)) / ((y + ( sqrt ((y ^2 ) + 1))) * (( sqrt ((y ^2 ) + 1)) - y))))) by A2, XCMPLX_1: 91

      .= ( log ( number_e ,(((x + ( sqrt ((x ^2 ) + 1))) * (( sqrt ((y ^2 ) + 1)) - y)) / ((( sqrt ((y ^2 ) + 1)) ^2 ) - (y ^2 )))))

      .= ( log ( number_e ,(((x + ( sqrt ((x ^2 ) + 1))) * (( sqrt ((y ^2 ) + 1)) - y)) / (((y ^2 ) + 1) - (y ^2 ))))) by A3, SQUARE_1:def 2

      .= ( log ( number_e ,((((x * ( sqrt ((y ^2 ) + 1))) - (y * ( sqrt ((x ^2 ) + 1)))) + (( sqrt ((x ^2 ) + 1)) * ( sqrt ((y ^2 ) + 1)))) - (x * y))));

      hence thesis by A4, A5;

    end;

    theorem :: SIN_COS7:52

    1 <= x & 1 <= y implies (( cosh1" x) + ( cosh1" y)) = ( cosh1" ((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))

    proof

      assume that

       A1: 1 <= x and

       A2: 1 <= y;

      

       A3: ((y ^2 ) - 1) >= 0 by A2, Lm3;

      set t = ((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1))));

      

       A4: ((x ^2 ) - 1) >= 0 by A1, Lm3;

      t = ( sqrt (((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) ^2 )) by A1, A2, Th24, SQUARE_1: 22

      .= ( sqrt ((((x ^2 ) * (( sqrt ((y ^2 ) - 1)) ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y * ( sqrt ((x ^2 ) - 1))) ^2 )))

      .= ( sqrt ((((x ^2 ) * ((y ^2 ) - 1)) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y * ( sqrt ((x ^2 ) - 1))) ^2 ))) by A3, SQUARE_1:def 2

      .= ( sqrt (((((x ^2 ) * (y ^2 )) - (x ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y ^2 ) * (( sqrt ((x ^2 ) - 1)) ^2 ))))

      .= ( sqrt (((((x ^2 ) * (y ^2 )) - (x ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y ^2 ) * ((x ^2 ) - 1)))) by A4, SQUARE_1:def 2

      .= ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))));

      

      then

       A5: ( log ( number_e ,((((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y)))) = ( log ( number_e ,((( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + (((2 * x) * y) * (( sqrt ((y ^2 ) - 1)) * ( sqrt ((x ^2 ) - 1)))))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y))))

      .= ( log ( number_e ,((( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + (((2 * x) * y) * ( sqrt (((y ^2 ) - 1) * ((x ^2 ) - 1)))))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y)))) by A4, A3, SQUARE_1: 29;

      

       A6: ( cosh1" ((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) = ( log ( number_e ,(((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) + ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))) ^2 )) - 1)))))

      .= ( log ( number_e ,(((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) + ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (((x ^2 ) - 1) * ((y ^2 ) - 1))) - 1))))) by A4, A3, SQUARE_1:def 2

      .= ( log ( number_e ,(( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + (((2 * x) * y) * ( sqrt (((y ^2 ) - 1) * ((x ^2 ) - 1)))))) + (( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))) + (x * y)))));

       0 < (x + ( sqrt ((x ^2 ) - 1))) & 0 < (y + ( sqrt ((y ^2 ) - 1))) by A1, A2, Th23;

      

      then (( cosh1" x) + ( cosh1" y)) = ( log ( number_e ,((x + ( sqrt ((x ^2 ) - 1))) * (y + ( sqrt ((y ^2 ) - 1)))))) by Lm1, POWER: 53, TAYLOR_1: 11

      .= ( log ( number_e ,((((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) + (( sqrt ((x ^2 ) - 1)) * ( sqrt ((y ^2 ) - 1)))) + (x * y))))

      .= ( log ( number_e ,((((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y)))) by A4, A3, SQUARE_1: 29;

      hence thesis by A5, A6;

    end;

    theorem :: SIN_COS7:53

    1 <= x & 1 <= y implies (( cosh2" x) + ( cosh2" y)) = ( cosh2" ((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))

    proof

      assume that

       A1: 1 <= x and

       A2: 1 <= y;

      

       A3: ((y ^2 ) - 1) >= 0 by A2, Lm3;

      

       A4: 0 < (x + ( sqrt ((x ^2 ) - 1))) & 0 < (y + ( sqrt ((y ^2 ) - 1))) by A1, A2, Th23;

      set t = ((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1))));

      

       A5: ((x ^2 ) - 1) >= 0 by A1, Lm3;

      t = ( sqrt (((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) ^2 )) by A1, A2, Th24, SQUARE_1: 22

      .= ( sqrt ((((x ^2 ) * (( sqrt ((y ^2 ) - 1)) ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y * ( sqrt ((x ^2 ) - 1))) ^2 )))

      .= ( sqrt ((((x ^2 ) * ((y ^2 ) - 1)) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y * ( sqrt ((x ^2 ) - 1))) ^2 ))) by A3, SQUARE_1:def 2

      .= ( sqrt (((((x ^2 ) * (y ^2 )) - (x ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y ^2 ) * (( sqrt ((x ^2 ) - 1)) ^2 ))))

      .= ( sqrt (((((x ^2 ) * (y ^2 )) - (x ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))) + ((y ^2 ) * ((x ^2 ) - 1)))) by A5, SQUARE_1:def 2

      .= ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + ((2 * (x * ( sqrt ((y ^2 ) - 1)))) * (y * ( sqrt ((x ^2 ) - 1))))));

      

      then

       A6: ( - ( log ( number_e ,((((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y))))) = ( - ( log ( number_e ,((( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + (((2 * x) * y) * (( sqrt ((y ^2 ) - 1)) * ( sqrt ((x ^2 ) - 1)))))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y)))))

      .= ( - ( log ( number_e ,((( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + (((2 * x) * y) * ( sqrt (((y ^2 ) - 1) * ((x ^2 ) - 1)))))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y))))) by A5, A3, SQUARE_1: 29;

      

       A7: ( cosh2" ((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) = ( - ( log ( number_e ,(((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) + ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))) ^2 )) - 1))))))

      .= ( - ( log ( number_e ,(((x * y) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) + ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (((x ^2 ) - 1) * ((y ^2 ) - 1))) - 1)))))) by A5, A3, SQUARE_1:def 2

      .= ( - ( log ( number_e ,(( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) + (((2 * x) * y) * ( sqrt (((y ^2 ) - 1) * ((x ^2 ) - 1)))))) + (( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))) + (x * y))))));

      (( cosh2" x) + ( cosh2" y)) = (( - 1) * (( log ( number_e ,(x + ( sqrt ((x ^2 ) - 1))))) + ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1)))))))

      .= (( - 1) * ( log ( number_e ,((x + ( sqrt ((x ^2 ) - 1))) * (y + ( sqrt ((y ^2 ) - 1))))))) by A4, Lm1, POWER: 53, TAYLOR_1: 11

      .= ( - ( log ( number_e ,((((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) + (( sqrt ((x ^2 ) - 1)) * ( sqrt ((y ^2 ) - 1)))) + (x * y)))))

      .= ( - ( log ( number_e ,((((x * ( sqrt ((y ^2 ) - 1))) + (y * ( sqrt ((x ^2 ) - 1)))) + ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (x * y))))) by A5, A3, SQUARE_1: 29;

      hence thesis by A6, A7;

    end;

    theorem :: SIN_COS7:54

    1 <= x & 1 <= y & |.y.| <= |.x.| implies (( cosh1" x) - ( cosh1" y)) = ( cosh1" ((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))

    proof

      assume that

       A1: 1 <= x and

       A2: 1 <= y and

       A3: |.y.| <= |.x.|;

      

       A4: 0 <= ((x ^2 ) - 1) by A1, Lm3;

      set t = ((y * ( sqrt ((x ^2 ) - 1))) - (x * ( sqrt ((y ^2 ) - 1))));

      

       A5: (y - ( sqrt ((y ^2 ) - 1))) > 0 by A2, Th25;

      

       A6: 0 <= ((y ^2 ) - 1) by A2, Lm3;

       0 < (x + ( sqrt ((x ^2 ) - 1))) & 0 < (y + ( sqrt ((y ^2 ) - 1))) by A1, A2, Th23;

      

      then

       A7: (( cosh1" x) - ( cosh1" y)) = ( log ( number_e ,((x + ( sqrt ((x ^2 ) - 1))) / (y + ( sqrt ((y ^2 ) - 1)))))) by Lm1, POWER: 54, TAYLOR_1: 11

      .= ( log ( number_e ,(((x + ( sqrt ((x ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1)))) / ((y + ( sqrt ((y ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1))))))) by A5, XCMPLX_1: 91

      .= ( log ( number_e ,(((x + ( sqrt ((x ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1)))) / ((y ^2 ) - (( sqrt ((y ^2 ) - 1)) ^2 )))))

      .= ( log ( number_e ,(((x + ( sqrt ((x ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1)))) / ((y ^2 ) - ((y ^2 ) - 1))))) by A6, SQUARE_1:def 2

      .= ( log ( number_e ,((((x * y) - (x * ( sqrt ((y ^2 ) - 1)))) + (y * ( sqrt ((x ^2 ) - 1)))) - (( sqrt ((x ^2 ) - 1)) * ( sqrt ((y ^2 ) - 1))))))

      .= ( log ( number_e ,((((x * y) - (x * ( sqrt ((y ^2 ) - 1)))) + (y * ( sqrt ((x ^2 ) - 1)))) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))) by A4, A6, SQUARE_1: 29

      .= ( log ( number_e ,((((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (y * ( sqrt ((x ^2 ) - 1)))) - (x * ( sqrt ((y ^2 ) - 1))))));

      

       A8: ( cosh1" ((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) = ( log ( number_e ,(((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) - ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))) ^2 )) - 1)))))

      .= ( log ( number_e ,(((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) - ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (((x ^2 ) - 1) * ((y ^2 ) - 1))) - 1))))) by A4, A6, SQUARE_1:def 2

      .= ( log ( number_e ,(((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) - (((2 * x) * y) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))))));

      t = ( sqrt (((y * ( sqrt ((x ^2 ) - 1))) - (x * ( sqrt ((y ^2 ) - 1)))) ^2 )) by A1, A2, A3, Th26, SQUARE_1: 22

      .= ( sqrt ((((y ^2 ) * (( sqrt ((x ^2 ) - 1)) ^2 )) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x * ( sqrt ((y ^2 ) - 1))) ^2 )))

      .= ( sqrt ((((y ^2 ) * ((x ^2 ) - 1)) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x * ( sqrt ((y ^2 ) - 1))) ^2 ))) by A4, SQUARE_1:def 2

      .= ( sqrt (((((x * y) ^2 ) - (y ^2 )) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x ^2 ) * (( sqrt ((y ^2 ) - 1)) ^2 ))))

      .= ( sqrt (((((x * y) ^2 ) - (y ^2 )) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x ^2 ) * ((y ^2 ) - 1)))) by A6, SQUARE_1:def 2

      .= ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) - (((2 * x) * y) * (( sqrt ((x ^2 ) - 1)) * ( sqrt ((y ^2 ) - 1))))))

      .= ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) - (((2 * x) * y) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))) by A4, A6, SQUARE_1: 29;

      hence thesis by A7, A8;

    end;

    theorem :: SIN_COS7:55

    1 <= x & 1 <= y & |.y.| <= |.x.| implies (( cosh2" x) - ( cosh2" y)) = ( cosh2" ((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))

    proof

      assume that

       A1: 1 <= x and

       A2: 1 <= y and

       A3: |.y.| <= |.x.|;

      

       A4: 0 < (x + ( sqrt ((x ^2 ) - 1))) & 0 < (y + ( sqrt ((y ^2 ) - 1))) by A1, A2, Th23;

      

       A5: 0 <= ((y ^2 ) - 1) by A2, Lm3;

      set t = ((y * ( sqrt ((x ^2 ) - 1))) - (x * ( sqrt ((y ^2 ) - 1))));

      

       A6: (y - ( sqrt ((y ^2 ) - 1))) > 0 by A2, Th25;

      

       A7: 0 <= ((x ^2 ) - 1) by A1, Lm3;

      

       A8: ( cosh2" ((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) = ( - ( log ( number_e ,(((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) - ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))) ^2 )) - 1))))))

      .= ( - ( log ( number_e ,(((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt (((((x * y) ^2 ) - ((2 * (x * y)) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))) + (((x ^2 ) - 1) * ((y ^2 ) - 1))) - 1)))))) by A7, A5, SQUARE_1:def 2

      .= ( - ( log ( number_e ,(((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) - (((2 * x) * y) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))))))));

      

       A9: (( cosh2" x) - ( cosh2" y)) = ( - (( log ( number_e ,(x + ( sqrt ((x ^2 ) - 1))))) - ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1)))))))

      .= ( - ( log ( number_e ,((x + ( sqrt ((x ^2 ) - 1))) / (y + ( sqrt ((y ^2 ) - 1))))))) by A4, Lm1, POWER: 54, TAYLOR_1: 11

      .= ( - ( log ( number_e ,(((x + ( sqrt ((x ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1)))) / ((y + ( sqrt ((y ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1)))))))) by A6, XCMPLX_1: 91

      .= ( - ( log ( number_e ,(((x + ( sqrt ((x ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1)))) / ((y ^2 ) - (( sqrt ((y ^2 ) - 1)) ^2 ))))))

      .= ( - ( log ( number_e ,(((x + ( sqrt ((x ^2 ) - 1))) * (y - ( sqrt ((y ^2 ) - 1)))) / ((y ^2 ) - ((y ^2 ) - 1)))))) by A5, SQUARE_1:def 2

      .= ( - ( log ( number_e ,((((x * y) - (x * ( sqrt ((y ^2 ) - 1)))) + (y * ( sqrt ((x ^2 ) - 1)))) - (( sqrt ((x ^2 ) - 1)) * ( sqrt ((y ^2 ) - 1)))))))

      .= ( - ( log ( number_e ,((((x * y) - (x * ( sqrt ((y ^2 ) - 1)))) + (y * ( sqrt ((x ^2 ) - 1)))) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1))))))) by A7, A5, SQUARE_1: 29

      .= ( - ( log ( number_e ,((((x * y) - ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))) + (y * ( sqrt ((x ^2 ) - 1)))) - (x * ( sqrt ((y ^2 ) - 1)))))));

      t = ( sqrt (((y * ( sqrt ((x ^2 ) - 1))) - (x * ( sqrt ((y ^2 ) - 1)))) ^2 )) by A1, A2, A3, Th26, SQUARE_1: 22

      .= ( sqrt ((((y ^2 ) * (( sqrt ((x ^2 ) - 1)) ^2 )) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x * ( sqrt ((y ^2 ) - 1))) ^2 )))

      .= ( sqrt ((((y ^2 ) * ((x ^2 ) - 1)) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x * ( sqrt ((y ^2 ) - 1))) ^2 ))) by A7, SQUARE_1:def 2

      .= ( sqrt (((((x * y) ^2 ) - (y ^2 )) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x ^2 ) * (( sqrt ((y ^2 ) - 1)) ^2 ))))

      .= ( sqrt (((((x * y) ^2 ) - (y ^2 )) - ((2 * (y * ( sqrt ((x ^2 ) - 1)))) * (x * ( sqrt ((y ^2 ) - 1))))) + ((x ^2 ) * ((y ^2 ) - 1)))) by A5, SQUARE_1:def 2

      .= ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) - (((2 * x) * y) * (( sqrt ((x ^2 ) - 1)) * ( sqrt ((y ^2 ) - 1))))))

      .= ( sqrt ((((2 * ((x * y) ^2 )) - (x ^2 )) - (y ^2 )) - (((2 * x) * y) * ( sqrt (((x ^2 ) - 1) * ((y ^2 ) - 1)))))) by A7, A5, SQUARE_1: 29;

      hence thesis by A9, A8;

    end;

    theorem :: SIN_COS7:56

    (x ^2 ) < 1 & (y ^2 ) < 1 implies (( tanh" x) + ( tanh" y)) = ( tanh" ((x + y) / (1 + (x * y))))

    proof

      assume

       A1: (x ^2 ) < 1 & (y ^2 ) < 1;

      then

       A2: 0 < ((1 + x) / (1 - x)) & 0 < ((1 + y) / (1 - y)) by Lm4;

      

       A3: (( tanh" x) + ( tanh" y)) = ((1 / 2) * (( log ( number_e ,((1 + x) / (1 - x)))) + ( log ( number_e ,((1 + y) / (1 - y))))))

      .= ((1 / 2) * ( log ( number_e ,(((1 + x) / (1 - x)) * ((1 + y) / (1 - y)))))) by A2, Lm1, POWER: 53, TAYLOR_1: 11

      .= ((1 / 2) * ( log ( number_e ,(((1 + x) * (1 + y)) / ((1 - x) * (1 - y)))))) by XCMPLX_1: 76

      .= ((1 / 2) * ( log ( number_e ,((((1 + x) + y) + (x * y)) / (((1 + (x * y)) - x) - y)))));

      

       A4: ((x * y) + 1) <> 0 by A1, Th27;

      

      then ( tanh" ((x + y) / (1 + (x * y)))) = ((1 / 2) * ( log ( number_e ,((((x + y) + ((1 + (x * y)) * 1)) / (1 + (x * y))) / (1 - ((x + y) / (1 + (x * y)))))))) by XCMPLX_1: 113

      .= ((1 / 2) * ( log ( number_e ,(((((x + y) + 1) + (x * y)) / (1 + (x * y))) / (((1 * (1 + (x * y))) - (x + y)) / (1 + (x * y))))))) by A4, XCMPLX_1: 127

      .= ((1 / 2) * ( log ( number_e ,((((1 + x) + y) + (x * y)) / (((1 + (x * y)) - x) - y))))) by A4, XCMPLX_1: 55;

      hence thesis by A3;

    end;

    theorem :: SIN_COS7:57

    (x ^2 ) < 1 & (y ^2 ) < 1 implies (( tanh" x) - ( tanh" y)) = ( tanh" ((x - y) / (1 - (x * y))))

    proof

      assume

       A1: (x ^2 ) < 1 & (y ^2 ) < 1;

      then

       A2: 0 < ((1 + x) / (1 - x)) & 0 < ((1 + y) / (1 - y)) by Lm4;

      

       A3: (( tanh" x) - ( tanh" y)) = ((1 / 2) * (( log ( number_e ,((1 + x) / (1 - x)))) - ( log ( number_e ,((1 + y) / (1 - y))))))

      .= ((1 / 2) * ( log ( number_e ,(((1 + x) / (1 - x)) / ((1 + y) / (1 - y)))))) by A2, Lm1, POWER: 54, TAYLOR_1: 11

      .= ((1 / 2) * ( log ( number_e ,(((1 + x) * (1 - y)) / ((1 - x) * (1 + y)))))) by XCMPLX_1: 84

      .= ((1 / 2) * ( log ( number_e ,((((1 - y) + x) - (x * y)) / (((1 + y) - x) - (x * y))))));

      

       A4: (1 - (x * y)) <> 0 by A1, Th28;

      

      then ( tanh" ((x - y) / (1 - (x * y)))) = ((1 / 2) * ( log ( number_e ,((((x - y) + ((1 - (x * y)) * 1)) / (1 - (x * y))) / (1 - ((x - y) / (1 - (x * y)))))))) by XCMPLX_1: 113

      .= ((1 / 2) * ( log ( number_e ,(((((x - y) + 1) - (x * y)) / (1 - (x * y))) / (((1 * (1 - (x * y))) - (x - y)) / (1 - (x * y))))))) by A4, XCMPLX_1: 127

      .= ((1 / 2) * ( log ( number_e ,((((1 - y) + x) - (x * y)) / (((1 + y) - x) - (x * y)))))) by A4, XCMPLX_1: 55;

      hence thesis by A3;

    end;

    theorem :: SIN_COS7:58

     0 < x implies ( log ( number_e ,x)) = (2 * ( tanh" ((x - 1) / (x + 1))))

    proof

      assume

       A1: 0 < x;

      

      then (2 * ( tanh" ((x - 1) / (x + 1)))) = ( log ( number_e ,((((x - 1) + ((x + 1) * 1)) / (x + 1)) / (1 - ((x - 1) / (x + 1)))))) by XCMPLX_1: 113

      .= ( log ( number_e ,(((2 * x) / (x + 1)) / (((1 * (x + 1)) - (x - 1)) / (x + 1))))) by A1, XCMPLX_1: 127

      .= ( log ( number_e ,((2 * x) / 2))) by A1, XCMPLX_1: 55

      .= ( log ( number_e ,x));

      hence thesis;

    end;

    theorem :: SIN_COS7:59

     0 < x implies ( log ( number_e ,x)) = ( tanh" (((x ^2 ) - 1) / ((x ^2 ) + 1)))

    proof

      assume

       A1: 0 < x;

      

       A2: ((x ^2 ) + 1) > 0 by Lm6;

      

      then ( tanh" (((x ^2 ) - 1) / ((x ^2 ) + 1))) = ((1 / 2) * ( log ( number_e ,(((((x ^2 ) - 1) + (((x ^2 ) + 1) * 1)) / ((x ^2 ) + 1)) / (1 - (((x ^2 ) - 1) / ((x ^2 ) + 1))))))) by XCMPLX_1: 113

      .= ((1 / 2) * ( log ( number_e ,(((2 * (x ^2 )) / ((x ^2 ) + 1)) / (((1 * ((x ^2 ) + 1)) - ((x ^2 ) - 1)) / ((x ^2 ) + 1)))))) by A2, XCMPLX_1: 127

      .= ((1 / 2) * ( log ( number_e ,((2 * (x ^2 )) / 2)))) by A2, XCMPLX_1: 55

      .= ((1 / 2) * ( log ( number_e ,(x to_power 2)))) by POWER: 46

      .= ((1 / 2) * (2 * ( log ( number_e ,x)))) by A1, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( log ( number_e ,x));

      hence thesis;

    end;

    theorem :: SIN_COS7:60

    1 < x implies ( log ( number_e ,x)) = ( cosh1" (((x ^2 ) + 1) / (2 * x)))

    proof

      assume

       A1: 1 < x;

      then x < (x ^2 ) by SQUARE_1: 14;

      then 1 < (x ^2 ) by A1, XXREAL_0: 2;

      then

       A2: (1 - 1) < ((x ^2 ) - 1) by XREAL_1: 14;

      (1 * 2) < (2 * x) by A1, XREAL_1: 68;

      then 1 < (2 * x) by XXREAL_0: 2;

      then

       A3: (1 ^2 ) < ((2 * x) ^2 ) by SQUARE_1: 16;

      ( cosh1" (((x ^2 ) + 1) / (2 * x))) = ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + ( sqrt (((((x ^2 ) + 1) ^2 ) / ((2 * x) ^2 )) - 1))))) by XCMPLX_1: 76

      .= ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + ( sqrt ((((((x ^2 ) ^2 ) + (2 * (x ^2 ))) + 1) - (1 * ((2 * x) ^2 ))) / ((2 * x) ^2 )))))) by A3, XCMPLX_1: 126

      .= ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + (( sqrt (((x ^2 ) - 1) ^2 )) / ( sqrt ((2 * x) ^2 )))))) by A1, A2, SQUARE_1: 30

      .= ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + (((x ^2 ) - 1) / ( sqrt ((2 * x) ^2 )))))) by A2, SQUARE_1: 22

      .= ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + (((x ^2 ) - 1) / (2 * x))))) by A1, SQUARE_1: 22

      .= ( log ( number_e ,((((x ^2 ) + 1) + ((x ^2 ) - 1)) / (2 * x))))

      .= ( log ( number_e ,((2 * (x ^2 )) / (2 * x))))

      .= ( log ( number_e ,((x * x) / x))) by XCMPLX_1: 91

      .= ( log ( number_e ,(x / (x / x)))) by XCMPLX_1: 77

      .= ( log ( number_e ,(x / 1))) by A1, XCMPLX_1: 60

      .= ( log ( number_e ,x));

      hence thesis;

    end;

    theorem :: SIN_COS7:61

     0 < x & x < 1 & 1 <= (((x ^2 ) + 1) / (2 * x)) implies ( log ( number_e ,x)) = ( cosh2" (((x ^2 ) + 1) / (2 * x)))

    proof

      assume that

       A1: 0 < x and

       A2: x < 1 and 1 <= (((x ^2 ) + 1) / (2 * x));

      

       A3: (1 / x) = (x to_power ( - 1)) by A1, Th1;

      (x ^2 ) < x by A1, A2, SQUARE_1: 13;

      then (x ^2 ) < 1 by A2, XXREAL_0: 2;

      then

       A4: ((x ^2 ) - (x ^2 )) < (1 - (x ^2 )) by XREAL_1: 14;

      ( 0 * 2) < (x * 2) by A1;

      then

       A5: 0 < ((2 * x) ^2 );

      ( cosh2" (((x ^2 ) + 1) / (2 * x))) = ( - ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + ( sqrt (((((x ^2 ) + 1) ^2 ) / ((2 * x) ^2 )) - 1)))))) by XCMPLX_1: 76

      .= ( - ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + ( sqrt ((((((x ^2 ) ^2 ) + (2 * (x ^2 ))) + 1) - (1 * ((2 * x) ^2 ))) / ((2 * x) ^2 ))))))) by A5, XCMPLX_1: 126

      .= ( - ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + (( sqrt ((1 - (x ^2 )) ^2 )) / ( sqrt ((2 * x) ^2 ))))))) by A1, A4, SQUARE_1: 30

      .= ( - ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + ((1 - (x ^2 )) / ( sqrt ((2 * x) ^2 ))))))) by A4, SQUARE_1: 22

      .= ( - ( log ( number_e ,((((x ^2 ) + 1) / (2 * x)) + ((1 - (x ^2 )) / (2 * x)))))) by A1, SQUARE_1: 22

      .= ( - ( log ( number_e ,((((x ^2 ) + 1) + (1 - (x ^2 ))) / (2 * x)))))

      .= ( - ( log ( number_e ,((2 * 1) / (2 * x)))))

      .= ( - ( log ( number_e ,(1 / x)))) by XCMPLX_1: 91

      .= ( - (( - 1) * ( log ( number_e ,x)))) by A1, A3, Lm1, POWER: 55, TAYLOR_1: 11

      .= ( log ( number_e ,x));

      hence thesis;

    end;

    theorem :: SIN_COS7:62

     0 < x implies ( log ( number_e ,x)) = ( sinh" (((x ^2 ) - 1) / (2 * x)))

    proof

      

       A1: (x ^2 ) >= 0 by XREAL_1: 63;

      assume

       A2: 0 < x;

      then ( 0 * 2) < (x * 2);

      then

       A3: 0 < ((2 * x) ^2 );

      ( sinh" (((x ^2 ) - 1) / (2 * x))) = ( log ( number_e ,((((x ^2 ) - 1) / (2 * x)) + ( sqrt (((((x ^2 ) - 1) ^2 ) / ((2 * x) ^2 )) + 1))))) by XCMPLX_1: 76

      .= ( log ( number_e ,((((x ^2 ) - 1) / (2 * x)) + ( sqrt ((((((x ^2 ) ^2 ) - (2 * (x ^2 ))) + 1) + (((2 * x) ^2 ) * 1)) / ((2 * x) ^2 )))))) by A3, XCMPLX_1: 113

      .= ( log ( number_e ,((((x ^2 ) - 1) / (2 * x)) + (( sqrt (((x ^2 ) + 1) ^2 )) / ( sqrt ((2 * x) ^2 )))))) by A2, SQUARE_1: 30

      .= ( log ( number_e ,((((x ^2 ) - 1) / (2 * x)) + (((x ^2 ) + 1) / ( sqrt ((2 * x) ^2 )))))) by A1, SQUARE_1: 22

      .= ( log ( number_e ,((((x ^2 ) - 1) / (2 * x)) + (((x ^2 ) + 1) / (2 * x))))) by A2, SQUARE_1: 22

      .= ( log ( number_e ,((((x ^2 ) - 1) + ((x ^2 ) + 1)) / (2 * x))))

      .= ( log ( number_e ,((2 * (x ^2 )) / (2 * x))))

      .= ( log ( number_e ,((x * x) / x))) by XCMPLX_1: 91

      .= ( log ( number_e ,(x / (x / x)))) by XCMPLX_1: 77

      .= ( log ( number_e ,(x / 1))) by A2, XCMPLX_1: 60

      .= ( log ( number_e ,x));

      hence thesis;

    end;

    theorem :: SIN_COS7:63

    y = ((1 / 2) * (( exp_R x) - ( exp_R ( - x)))) implies x = ( log ( number_e ,(y + ( sqrt ((y ^2 ) + 1)))))

    proof

      

       A1: ( exp_R x) > 0 by SIN_COS: 55;

      set t = ( exp_R x);

      

       A2: ( delta (1,( - (2 * y)),( - 1))) = (((( - 2) * y) ^2 ) - ((4 * 1) * ( - 1))) by QUIN_1:def 1

      .= ((4 * (y ^2 )) + 4);

      

       A3: 0 <= (y ^2 ) by XREAL_1: 63;

      assume y = ((1 / 2) * (( exp_R x) - ( exp_R ( - x))));

      then ((2 * y) * ( exp_R x)) = ((( exp_R x) - (1 / ( exp_R x))) * ( exp_R x)) by TAYLOR_1: 4;

      then ((2 * y) * t) = ((t ^2 ) - ((t * 1) / t));

      then (((2 * y) * t) - ((2 * y) * t)) = (((t ^2 ) - 1) - ((2 * y) * t)) by A1, XCMPLX_1: 60;

      then (((1 * (t ^2 )) + (( - (2 * y)) * t)) + ( - 1)) = 0 ;

      then t = ((( - ( - (2 * y))) + ( sqrt ( delta (1,( - (2 * y)),( - 1))))) / (2 * 1)) or t = ((( - ( - (2 * y))) - ( sqrt ( delta (1,( - (2 * y)),( - 1))))) / (2 * 1)) by A2, A3, QUIN_1: 15;

      then t = (((2 * y) + (( sqrt 4) * ( sqrt ((y ^2 ) + 1)))) / 2) or t = (((2 * y) - ( sqrt (4 * ((y ^2 ) + 1)))) / 2) by A2, A3, SQUARE_1: 29;

      then t = (((2 * y) + (2 * ( sqrt ((y ^2 ) + 1)))) / 2) or t = (((2 * y) - (2 * ( sqrt ((y ^2 ) + 1)))) / 2) by A3, SQUARE_1: 20, SQUARE_1: 29;

      then

       A4: ( exp_R x) = (y + ( sqrt ((y ^2 ) + 1))) or ( exp_R x) = (y - ( sqrt ((y ^2 ) + 1)));

      y < (( sqrt ((y ^2 ) + 1)) + 0 ) by Lm8;

      hence thesis by A1, A4, TAYLOR_1: 12, XREAL_1: 19;

    end;

    theorem :: SIN_COS7:64

    y = ((1 / 2) * (( exp_R x) + ( exp_R ( - x)))) & 1 <= y implies x = ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1))))) or x = ( - ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1))))))

    proof

      assume that

       A1: y = ((1 / 2) * (( exp_R x) + ( exp_R ( - x)))) and

       A2: 1 <= y;

      

       A3: (y + ( sqrt ((y ^2 ) - 1))) > 0 by A2, Lm10;

      set t = ( exp_R x);

      ((2 * y) * ( exp_R x)) = ((( exp_R x) + (1 / ( exp_R x))) * ( exp_R x)) by A1, TAYLOR_1: 4;

      then 0 < ( exp_R x) & ((2 * y) * t) = ((t ^2 ) + ((t * 1) / t)) by SIN_COS: 55;

      then (((2 * y) * t) - ((2 * y) * t)) = (((t ^2 ) + 1) - ((2 * y) * t)) by XCMPLX_1: 60;

      then

       A4: 0 = (((1 * (t ^2 )) + (( - (2 * y)) * t)) + 1);

      

       A5: ( delta (1,( - (2 * y)),1)) = (((( - 2) * y) ^2 ) - ((4 * 1) * 1)) by QUIN_1:def 1

      .= ((4 * (y ^2 )) - 4);

      

       A6: 0 <= ((y ^2 ) - 1) by A2, Lm3;

      then ( 0 * 4) <= (((y ^2 ) - 1) * 4);

      then t = ((( - ( - (2 * y))) + ( sqrt ( delta (1,( - (2 * y)),1)))) / (2 * 1)) or t = ((( - ( - (2 * y))) - ( sqrt ( delta (1,( - (2 * y)),1)))) / (2 * 1)) by A4, A5, QUIN_1: 15;

      then t = (((2 * y) + (( sqrt 4) * ( sqrt ((y ^2 ) - 1)))) / 2) or t = (((2 * y) - ( sqrt (4 * ((y ^2 ) - 1)))) / 2) by A6, A5, SQUARE_1: 29;

      then t = (((2 * y) + (2 * ( sqrt ((y ^2 ) - 1)))) / 2) or t = (((2 * y) - (2 * ( sqrt ((y ^2 ) - 1)))) / 2) by A6, SQUARE_1: 20, SQUARE_1: 29;

      then ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1))))) = x or ( log ( number_e ,(y - ( sqrt ((y ^2 ) - 1))))) = x by TAYLOR_1: 12;

      then ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1))))) = x or ( log ( number_e ,(((y - ( sqrt ((y ^2 ) - 1))) * (y + ( sqrt ((y ^2 ) - 1)))) / (y + ( sqrt ((y ^2 ) - 1)))))) = x by A3, XCMPLX_1: 89;

      then ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1))))) = x or ( log ( number_e ,(((y ^2 ) - (( sqrt ((y ^2 ) - 1)) ^2 )) / (y + ( sqrt ((y ^2 ) - 1)))))) = x;

      then

       A7: ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1))))) = x or ( log ( number_e ,(((y ^2 ) - ((y ^2 ) - 1)) / (y + ( sqrt ((y ^2 ) - 1)))))) = x by A6, SQUARE_1:def 2;

      (1 / (y + ( sqrt ((y ^2 ) - 1)))) = ((y + ( sqrt ((y ^2 ) - 1))) to_power ( - 1)) by A3, Th1;

      then ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1))))) = x or (( - 1) * ( log ( number_e ,(y + ( sqrt ((y ^2 ) - 1)))))) = x by A3, A7, Lm1, POWER: 55, TAYLOR_1: 11;

      hence thesis;

    end;

    theorem :: SIN_COS7:65

    y = ((( exp_R x) - ( exp_R ( - x))) / (( exp_R x) + ( exp_R ( - x)))) implies x = ((1 / 2) * ( log ( number_e ,((1 + y) / (1 - y)))))

    proof

      

       A1: 0 < ( exp_R x) by SIN_COS: 55;

      set t = ( exp_R x);

      assume y = ((( exp_R x) - ( exp_R ( - x))) / (( exp_R x) + ( exp_R ( - x))));

      then y = ((( exp_R x) - (1 / ( exp_R x))) / (( exp_R x) + ( exp_R ( - x)))) by TAYLOR_1: 4;

      then y = ((( exp_R x) - (1 / ( exp_R x))) / (( exp_R x) + (1 / ( exp_R x)))) by TAYLOR_1: 4;

      then y = ((((( exp_R x) * ( exp_R x)) - 1) / ( exp_R x)) / (( exp_R x) + (1 / ( exp_R x)))) by A1, XCMPLX_1: 127;

      then y = ((((( exp_R x) ^2 ) - 1) / ( exp_R x)) / ((1 + (( exp_R x) * ( exp_R x))) / ( exp_R x))) by A1, XCMPLX_1: 113;

      then

       A2: y = (((( exp_R x) ^2 ) - 1) / (1 + (( exp_R x) ^2 ))) by A1, XCMPLX_1: 55;

      then ((1 * y) + ((t ^2 ) * y)) = ((((t ^2 ) - 1) / (1 + (t ^2 ))) * (1 + (t ^2 )));

      then ((y + ((t ^2 ) * y)) - ((t ^2 ) - 1)) = (((t ^2 ) - 1) - ((t ^2 ) - 1)) by A1, XCMPLX_1: 87;

      then (((t ^2 ) * (y - 1)) / (y - 1)) = (( - (y + 1)) / (y - 1));

      then

       A3: (((t ^2 ) * (y - 1)) / (y - 1)) = ((y + 1) / ( - (y - 1))) by XCMPLX_1: 192;

      (y - 1) <> 0 by A2, Th31;

      then ( sqrt (t ^2 )) = ( sqrt ((y + 1) / (1 - y))) by A3, XCMPLX_1: 89;

      then

       A4: ( exp_R x) = ( sqrt ((y + 1) / (1 - y))) by A1, SQUARE_1: 22;

      ( - 1) < y by A2, Lm11, SIN_COS: 55;

      then

       A5: 0 < ((y + 1) / (1 - y)) by A2, Th31, Th32;

      then ( sqrt ((y + 1) / (1 - y))) = (((y + 1) / (1 - y)) to_power (1 / 2)) by ASYMPT_1: 83;

      then ( log ( number_e ,(((y + 1) / (1 - y)) to_power (1 / 2)))) = x by A4, TAYLOR_1: 12;

      hence thesis by A5, Lm1, POWER: 55, TAYLOR_1: 11;

    end;

    theorem :: SIN_COS7:66

    y = ((( exp_R x) + ( exp_R ( - x))) / (( exp_R x) - ( exp_R ( - x)))) & x <> 0 implies x = ((1 / 2) * ( log ( number_e ,((y + 1) / (y - 1)))))

    proof

      

       A1: 0 < ( exp_R x) by SIN_COS: 55;

      set t = ( exp_R x);

      assume that

       A2: y = ((( exp_R x) + ( exp_R ( - x))) / (( exp_R x) - ( exp_R ( - x)))) and

       A3: x <> 0 ;

      y = ((( exp_R x) + (1 / ( exp_R x))) / (( exp_R x) - ( exp_R ( - x)))) by A2, TAYLOR_1: 4;

      then y = ((( exp_R x) + (1 / ( exp_R x))) / (( exp_R x) - (1 / ( exp_R x)))) by TAYLOR_1: 4;

      then y = ((( exp_R x) + (1 / ( exp_R x))) / (((( exp_R x) * ( exp_R x)) - 1) / ( exp_R x))) by A1, XCMPLX_1: 127;

      then y = (((1 + (( exp_R x) * ( exp_R x))) / ( exp_R x)) / (((( exp_R x) ^2 ) - 1) / ( exp_R x))) by A1, XCMPLX_1: 113;

      then

       A4: y = ((1 + (( exp_R x) ^2 )) / ((( exp_R x) ^2 ) - 1)) by A1, XCMPLX_1: 55;

      then (y * ((t ^2 ) - 1)) = (1 + (t ^2 )) by A3, Th30, XCMPLX_1: 87;

      then

       A5: (((t ^2 ) * (y - 1)) / (y - 1)) = ((y + 1) / (y - 1));

      ( exp_R x) <> 1 by A3, Th29;

      then

       A6: 1 < y or y < ( - 1) by A4, Lm12, SIN_COS: 55;

      then (1 - 1) < (y - 1) or (y - 1) < (( - 1) - 1) by XREAL_1: 14;

      then ( sqrt (t ^2 )) = ( sqrt ((y + 1) / (y - 1))) by A5, XCMPLX_1: 89;

      then

       A7: ( exp_R x) = ( sqrt ((y + 1) / (y - 1))) by A1, SQUARE_1: 22;

      

       A8: 0 < ((y + 1) / (y - 1)) by A6, Lm7;

      then ( sqrt ((y + 1) / (y - 1))) = (((y + 1) / (y - 1)) to_power (1 / 2)) by ASYMPT_1: 83;

      then ( log ( number_e ,(((y + 1) / (y - 1)) to_power (1 / 2)))) = x by A7, TAYLOR_1: 12;

      hence thesis by A8, Lm1, POWER: 55, TAYLOR_1: 11;

    end;

    theorem :: SIN_COS7:67

    y = (1 / ((( exp_R x) + ( exp_R ( - x))) / 2)) implies x = ( log ( number_e ,((1 + ( sqrt (1 - (y ^2 )))) / y))) or x = ( - ( log ( number_e ,((1 + ( sqrt (1 - (y ^2 )))) / y))))

    proof

      set t = ( exp_R x);

      

       A1: ( delta (y,( - 2),y)) = ((( - 2) ^2 ) - ((4 * y) * y)) by QUIN_1:def 1

      .= (4 - (4 * (y ^2 )));

      assume y = (1 / ((( exp_R x) + ( exp_R ( - x))) / 2));

      then y = ((1 * 2) / (2 * ((( exp_R x) + ( exp_R ( - x))) / 2))) by XCMPLX_1: 91;

      then 0 < ( exp_R x) & y = (2 / (( exp_R x) + (1 / ( exp_R x)))) by SIN_COS: 55, TAYLOR_1: 4;

      then y = (2 / ((1 + (( exp_R x) * ( exp_R x))) / ( exp_R x))) by XCMPLX_1: 113;

      then y = (2 * (( exp_R x) / (1 + (( exp_R x) ^2 )))) by XCMPLX_1: 79;

      then

       A2: y = ((2 * t) / (1 + (t ^2 )));

      then

       A3: 0 < y by Lm13, SIN_COS: 55;

      (1 + (t ^2 )) > 0 by Lm6;

      then

       A4: (y * (1 + (t ^2 ))) = (2 * t) by A2, XCMPLX_1: 87;

      

       A5: y <= 1 by A2, Lm14, SIN_COS: 55;

      then

       A6: 0 <= (1 - (y ^2 )) by A3, Lm16;

      ( Polynom (y,( - 2),y,t)) = (((y * (t ^2 )) + (( - 2) * t)) + y) by POLYEQ_1:def 2;

      then t = ((( - ( - 2)) + ( sqrt ( delta (y,( - 2),y)))) / (2 * y)) or t = ((( - ( - 2)) - ( sqrt ( delta (y,( - 2),y)))) / (2 * y)) by A3, A5, A4, A1, Lm17, QUIN_1: 15;

      then t = ((2 + ( sqrt (4 * (1 - (y ^2 ))))) / (2 * y)) or t = ((2 - ( sqrt (4 * (1 - (y ^2 ))))) / (2 * y)) by A1;

      then t = ((2 + (2 * ( sqrt (1 - (y ^2 ))))) / (2 * y)) or t = ((2 - (2 * ( sqrt (1 - (y ^2 ))))) / (2 * y)) by A6, SQUARE_1: 20, SQUARE_1: 29;

      then t = ((2 * (1 + ( sqrt (1 - (y ^2 ))))) / (2 * y)) or t = ((2 * (1 - ( sqrt (1 - (y ^2 ))))) / (2 * y));

      then

       A7: t = ((1 + ( sqrt (1 - (y ^2 )))) / y) or t = ((1 - ( sqrt (1 - (y ^2 )))) / y) by XCMPLX_1: 91;

       0 < (1 + ( sqrt (1 - (y ^2 )))) by A3, A5, Lm18;

      then t = ((1 + ( sqrt (1 - (y ^2 )))) / y) or t = (((1 - ( sqrt (1 - (y ^2 )))) * (1 + ( sqrt (1 - (y ^2 ))))) / (y * (1 + ( sqrt (1 - (y ^2 )))))) by A7, XCMPLX_1: 91;

      then t = ((1 + ( sqrt (1 - (y ^2 )))) / y) or t = ((1 - (( sqrt (1 - (y ^2 ))) ^2 )) / (y * (1 + ( sqrt (1 - (y ^2 ))))));

      then t = ((1 + ( sqrt (1 - (y ^2 )))) / y) or t = ((1 - (1 - (y ^2 ))) / (y * (1 + ( sqrt (1 - (y ^2 )))))) by A6, SQUARE_1:def 2;

      then

       A8: t = ((1 + ( sqrt (1 - (y ^2 )))) / y) or t = (y / (1 + ( sqrt (1 - (y ^2 ))))) by A3, XCMPLX_1: 91;

      ( log ( number_e ,( exp_R x))) = x & (1 / ((1 + ( sqrt (1 - (y ^2 )))) / y)) = (((1 + ( sqrt (1 - (y ^2 )))) / y) to_power ( - 1)) by A3, A5, Lm19, Th1, TAYLOR_1: 12;

      then

       A9: ( log ( number_e ,((1 + ( sqrt (1 - (y ^2 )))) / y))) = x or ( log ( number_e ,(((1 + ( sqrt (1 - (y ^2 )))) / y) to_power ( - 1)))) = x by A8, XCMPLX_1: 57;

       0 < ((1 + ( sqrt (1 - (y ^2 )))) / y) by A3, A5, Lm19;

      then ( log ( number_e ,((1 + ( sqrt (1 - (y ^2 )))) / y))) = x or (( - 1) * ( log ( number_e ,((1 + ( sqrt (1 - (y ^2 )))) / y)))) = x by A9, Lm1, POWER: 55, TAYLOR_1: 11;

      hence thesis;

    end;

    theorem :: SIN_COS7:68

    y = (1 / ((( exp_R x) - ( exp_R ( - x))) / 2)) & x <> 0 implies x = ( log ( number_e ,((1 + ( sqrt (1 + (y ^2 )))) / y))) or x = ( log ( number_e ,((1 - ( sqrt (1 + (y ^2 )))) / y)))

    proof

      

       A1: 0 < ( exp_R x) by SIN_COS: 55;

      set t = ( exp_R x);

      assume that

       A2: y = (1 / ((( exp_R x) - ( exp_R ( - x))) / 2)) and

       A3: x <> 0 ;

      

       A4: ( delta (y,( - 2),( - y))) = ((( - 2) ^2 ) - ((4 * y) * ( - y))) by QUIN_1:def 1

      .= (4 + (4 * (y ^2 )));

      y = ((1 * 2) / (2 * ((( exp_R x) - ( exp_R ( - x))) / 2))) by A2, XCMPLX_1: 91;

      then y = (2 / (( exp_R x) - (1 / ( exp_R x)))) by TAYLOR_1: 4;

      then y = (2 / (((( exp_R x) * ( exp_R x)) - 1) / ( exp_R x))) by A1, XCMPLX_1: 127;

      then

       A5: y = (2 * (( exp_R x) / ((( exp_R x) ^2 ) - 1))) by XCMPLX_1: 79;

      then

       A6: y = ((2 * ( exp_R x)) / ((( exp_R x) ^2 ) - 1));

      then (y * ((t ^2 ) - 1)) = (2 * t) by A3, Th30, XCMPLX_1: 87;

      then

       A7: (((y * (t ^2 )) + (( - 2) * t)) + ( - y)) = 0 ;

      

       A8: ( exp_R x) <> 1 by A3, Th29;

      then

       A9: ((2 * ( exp_R x)) / ((( exp_R x) ^2 ) - 1)) <> 0 by Lm20, SIN_COS: 55;

      per cases by A9, A5;

        suppose

         A10: 0 < y;

        

         A11: 0 < (1 + (y ^2 )) by Lm6;

        then ( 0 * 4) < (4 * (1 + (y ^2 )));

        then t = ((2 + ( sqrt ( delta (y,( - 2),( - y))))) / (2 * y)) or t = ((( - ( - 2)) - ( sqrt ( delta (y,( - 2),( - y))))) / (2 * y)) by A1, A8, A6, A7, A4, Lm20, QUIN_1: 15;

        then t = ((2 + (( sqrt 4) * ( sqrt (1 + (y ^2 ))))) / (2 * y)) or t = ((2 - ( sqrt (4 * (1 + (y ^2 ))))) / (2 * y)) by A4, A11, SQUARE_1: 29;

        then t = ((2 * (1 + ( sqrt (1 + (y ^2 ))))) / (2 * y)) or t = ((2 - (2 * ( sqrt (1 + (y ^2 ))))) / (2 * y)) by A11, SQUARE_1: 20, SQUARE_1: 29;

        then

         A12: t = ((1 + ( sqrt (1 + (y ^2 )))) / y) or t = ((2 * (1 - ( sqrt (1 + (y ^2 ))))) / (2 * y)) by XCMPLX_1: 91;

        ((1 - ( sqrt (1 + (y ^2 )))) / y) < 0 by A10, Lm15;

        hence thesis by A1, A12, TAYLOR_1: 12, XCMPLX_1: 91;

      end;

        suppose

         A13: y < 0 ;

        

         A14: 0 < (1 + (y ^2 )) by Lm6;

        then ( 0 * 4) < (4 * (1 + (y ^2 )));

        then t = ((2 + ( sqrt ( delta (y,( - 2),( - y))))) / (2 * y)) or t = ((( - ( - 2)) - ( sqrt ( delta (y,( - 2),( - y))))) / (2 * y)) by A1, A8, A6, A7, A4, Lm20, QUIN_1: 15;

        then t = ((2 + (( sqrt 4) * ( sqrt (1 + (y ^2 ))))) / (2 * y)) or t = ((2 - ( sqrt (4 * (1 + (y ^2 ))))) / (2 * y)) by A4, A14, SQUARE_1: 29;

        then t = ((2 * (1 + ( sqrt (1 + (y ^2 ))))) / (2 * y)) or t = ((2 - (2 * ( sqrt (1 + (y ^2 ))))) / (2 * y)) by A14, SQUARE_1: 20, SQUARE_1: 29;

        then

         A15: t = ((1 + ( sqrt (1 + (y ^2 )))) / y) or t = ((2 * (1 - ( sqrt (1 + (y ^2 ))))) / (2 * y)) by XCMPLX_1: 91;

        ((1 + ( sqrt (1 + (y ^2 )))) / y) < 0 by A13, Lm21;

        then ( exp_R x) = ((1 - ( sqrt (1 + (y ^2 )))) / y) by A15, SIN_COS: 55, XCMPLX_1: 91;

        hence thesis by TAYLOR_1: 12;

      end;

    end;

    theorem :: SIN_COS7:69

    

     Th69: ( cosh . (2 * x)) = (1 + (2 * (( sinh . x) ^2 )))

    proof

      (2 * (( sinh . x) ^2 )) = (2 * ((1 / 2) * (( cosh . (2 * x)) - 1))) by SIN_COS2: 18;

      hence thesis;

    end;

    theorem :: SIN_COS7:70

    

     Th70: (( cosh . x) ^2 ) = (1 + (( sinh . x) ^2 ))

    proof

      ( cosh . (2 * x)) = ( cosh . (x + x))

      .= ((( cosh . x) ^2 ) + (( sinh . x) ^2 )) by SIN_COS2: 20;

      then ((1 + (2 * (( sinh . x) ^2 ))) - (( sinh . x) ^2 )) = (((( cosh . x) ^2 ) + (( sinh . x) ^2 )) - (( sinh . x) ^2 )) by Th69;

      hence thesis;

    end;

    theorem :: SIN_COS7:71

    

     Th71: (( sinh . x) ^2 ) = ((( cosh . x) ^2 ) - 1)

    proof

      (((( cosh . x) ^2 ) - (( sinh . x) ^2 )) - 1) = (1 - 1) by SIN_COS2: 14;

      hence thesis;

    end;

    theorem :: SIN_COS7:72

    ( sinh (5 * x)) = (((5 * ( sinh x)) + (20 * (( sinh x) |^ 3))) + (16 * (( sinh x) |^ 5)))

    proof

      set t = ( sinh . x);

      ( sinh (5 * x)) = ( sinh . ((4 * x) + x)) by SIN_COS2:def 2

      .= ((( sinh . (2 * (2 * x))) * ( cosh . x)) + (( cosh . (4 * x)) * t)) by SIN_COS2: 21

      .= ((((2 * ( sinh . (2 * x))) * ( cosh . (2 * x))) * ( cosh . x)) + (( cosh . (4 * x)) * t)) by SIN_COS2: 23

      .= ((((2 * ((2 * t) * ( cosh . x))) * ( cosh . (2 * x))) * ( cosh . x)) + (( cosh . (4 * x)) * t)) by SIN_COS2: 23

      .= ((((4 * t) * (( cosh . x) ^2 )) * ( cosh . (2 * x))) + (( cosh . (4 * x)) * t))

      .= ((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + (( cosh . (2 * (2 * x))) * t)) by Th69

      .= ((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + ((1 + (2 * (( sinh . (2 * x)) ^2 ))) * t)) by Th69

      .= ((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + ((1 + (2 * (((2 * t) * ( cosh . x)) ^2 ))) * t)) by SIN_COS2: 23

      .= (((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + t) + (((8 * (t ^2 )) * t) * (( cosh . x) ^2 )))

      .= (((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + t) + (((8 * ((t |^ 1) * t)) * t) * (( cosh . x) ^2 )))

      .= (((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + t) + (((8 * (t |^ (1 + 1))) * t) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= (((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + t) + ((8 * ((t |^ 2) * t)) * (( cosh . x) ^2 )))

      .= (((((4 * t) * (( cosh . x) ^2 )) * (1 + (2 * (t ^2 )))) + t) + ((8 * (t |^ (2 + 1))) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= ((((((4 * t) * (( cosh . x) ^2 )) * 1) + ((((4 * t) * (( cosh . x) ^2 )) * 2) * (t ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= ((((((4 * t) * (1 + (t ^2 ))) * 1) + (((8 * t) * (( cosh . x) ^2 )) * (t ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by Th70

      .= (((((4 * t) + (((4 * t) * t) * t)) + (((8 * t) * (( cosh . x) ^2 )) * (t ^2 ))) + ( sinh . x)) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + (((4 * (t |^ 1)) * t) * t)) + (((8 * t) * (( cosh . x) ^2 )) * (t ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + ((4 * ((t |^ 1) * t)) * t)) + (((8 * t) * (( cosh . x) ^2 )) * (t ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + ((4 * (t |^ (1 + 1))) * t)) + (((8 * t) * (( cosh . x) ^2 )) * (t ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= (((((4 * t) + (4 * ((t |^ 2) * t))) + (((8 * t) * (( cosh . x) ^2 )) * (t ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + (4 * (t |^ (2 + 1)))) + (((8 * t) * (( cosh . x) ^2 )) * (t ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= (((((4 * t) + (4 * (t |^ 3))) + ((((8 * t) * t) * t) * (( cosh . x) ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + (4 * (t |^ 3))) + ((((8 * (t |^ 1)) * t) * t) * (( cosh . x) ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + (4 * (t |^ 3))) + (((8 * ((t |^ 1) * t)) * t) * (( cosh . x) ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + (4 * (t |^ 3))) + (((8 * (t |^ (1 + 1))) * t) * (( cosh . x) ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= (((((4 * t) + (4 * (t |^ 3))) + ((8 * ((t |^ 2) * t)) * (( cosh . x) ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= (((((4 * t) + (4 * (t |^ 3))) + ((8 * (t |^ (2 + 1))) * (( cosh . x) ^2 ))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= (((((4 * t) + (4 * (t |^ 3))) + ((8 * (t |^ 3)) * (1 + (t ^2 )))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by Th70

      .= ((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + ((8 * ((t |^ 3) * t)) * t)) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= ((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + ((8 * (t |^ (3 + 1))) * t)) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= ((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + (8 * ((t |^ 4) * t))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 )))

      .= ((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + (8 * (t |^ (4 + 1)))) + t) + ((8 * (t |^ 3)) * (( cosh . x) ^2 ))) by NEWTON: 6

      .= ((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + (8 * (t |^ 5))) + t) + ((8 * (t |^ 3)) * (1 + (t ^2 )))) by Th70

      .= (((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + (8 * (t |^ 5))) + t) + (8 * (t |^ 3))) + ((8 * ((t |^ 3) * t)) * t))

      .= (((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + (8 * (t |^ 5))) + t) + (8 * (t |^ 3))) + ((8 * (t |^ (3 + 1))) * t)) by NEWTON: 6

      .= (((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + (8 * (t |^ 5))) + t) + (8 * (t |^ 3))) + (8 * ((t |^ 4) * t)))

      .= (((((((4 * t) + (4 * (t |^ 3))) + (8 * (t |^ 3))) + (8 * (t |^ 5))) + t) + (8 * (t |^ 3))) + (8 * (t |^ (4 + 1)))) by NEWTON: 6

      .= (((5 * t) + (20 * (t |^ 3))) + ((8 * (t |^ 5)) + (8 * (t |^ 5))))

      .= (((5 * ( sinh x)) + (20 * (t |^ 3))) + (16 * (t |^ 5))) by SIN_COS2:def 2

      .= (((5 * ( sinh x)) + (20 * (( sinh x) |^ 3))) + (16 * (t |^ 5))) by SIN_COS2:def 2

      .= (((5 * ( sinh x)) + (20 * (( sinh x) |^ 3))) + (16 * (( sinh x) |^ 5))) by SIN_COS2:def 2;

      hence thesis;

    end;

    theorem :: SIN_COS7:73

    ( cosh (5 * x)) = (((5 * ( cosh x)) - (20 * (( cosh x) |^ 3))) + (16 * (( cosh x) |^ 5)))

    proof

      set t = ( cosh . x), u = ( sinh . x);

      ( cosh (5 * x)) = ( cosh . ((4 * x) + x)) by SIN_COS2:def 4

      .= ((( cosh . (2 * (2 * x))) * t) + (( sinh . (4 * x)) * u)) by SIN_COS2: 20

      .= (((1 + (2 * (( sinh . (2 * x)) ^2 ))) * t) + (( sinh . (4 * x)) * u)) by Th69

      .= (((1 + (2 * (((2 * u) * t) ^2 ))) * t) + (( sinh . (2 * (2 * x))) * u)) by SIN_COS2: 23

      .= ((t + ((8 * (u ^2 )) * ((t ^2 ) * t))) + (( sinh . (2 * (2 * x))) * u))

      .= ((t + ((8 * (u ^2 )) * (((t |^ 1) * t) * t))) + (( sinh . (2 * (2 * x))) * u))

      .= ((t + ((8 * (u ^2 )) * ((t |^ (1 + 1)) * t))) + (( sinh . (2 * (2 * x))) * u)) by NEWTON: 6

      .= ((t + ((8 * (( sinh . x) ^2 )) * (t |^ (2 + 1)))) + (( sinh . (2 * (2 * x))) * u)) by NEWTON: 6

      .= ((t + ((8 * ((t ^2 ) - 1)) * (t |^ 3))) + (( sinh . (2 * (2 * x))) * u)) by Th71

      .= (((t + (8 * (((t |^ 3) * t) * t))) - (8 * (t |^ 3))) + (( sinh . (2 * (2 * x))) * u))

      .= (((t + (8 * ((t |^ (3 + 1)) * t))) - (8 * (t |^ 3))) + (( sinh . (2 * (2 * x))) * u)) by NEWTON: 6

      .= (((t + (8 * (t |^ (4 + 1)))) - (8 * (t |^ 3))) + (( sinh . (2 * (2 * x))) * u)) by NEWTON: 6

      .= (((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + (((2 * ( sinh . (2 * x))) * ( cosh . (2 * x))) * u)) by SIN_COS2: 23

      .= (((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + (((2 * ((2 * u) * t)) * ( cosh . (2 * x))) * u)) by SIN_COS2: 23

      .= (((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + (((4 * (u ^2 )) * t) * ( cosh . (2 * x))))

      .= (((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + (((4 * ((t ^2 ) - 1)) * t) * ( cosh . (2 * x)))) by Th71

      .= ((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + ((4 * ((t * t) * t)) * ( cosh . (2 * x)))) - ((4 * t) * ( cosh . (2 * x))))

      .= ((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + ((4 * (((t |^ 1) * t) * t)) * ( cosh . (2 * x)))) - ((4 * t) * ( cosh . (2 * x))))

      .= ((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + ((4 * ((t |^ (1 + 1)) * t)) * ( cosh . (2 * x)))) - ((4 * t) * ( cosh . (2 * x)))) by NEWTON: 6

      .= ((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + ((4 * (t |^ (2 + 1))) * ( cosh . (2 * x)))) - ((4 * t) * ( cosh . (2 * x)))) by NEWTON: 6

      .= ((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + ((4 * (t |^ 3)) * ((2 * (t ^2 )) - 1))) - ((4 * t) * ( cosh . (2 * x)))) by SIN_COS2: 23

      .= (((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + (8 * (((t |^ 3) * t) * t))) - (4 * (t |^ 3))) - ((4 * t) * ( cosh . (2 * x))))

      .= (((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + (8 * ((t |^ (3 + 1)) * t))) - (4 * (t |^ 3))) - ((4 * t) * ( cosh . (2 * x)))) by NEWTON: 6

      .= (((((t + (8 * (t |^ 5))) - (8 * (t |^ 3))) + (8 * (t |^ (4 + 1)))) - (4 * (t |^ 3))) - ((4 * t) * ( cosh . (2 * x)))) by NEWTON: 6

      .= (((t + (16 * (t |^ 5))) - (12 * (t |^ 3))) - ((4 * t) * ((2 * (t ^2 )) - 1))) by SIN_COS2: 23

      .= ((((5 * t) + (16 * (t |^ 5))) - (12 * (t |^ 3))) - (8 * ((t * t) * t)))

      .= ((((5 * t) + (16 * (t |^ 5))) - (12 * (t |^ 3))) - (8 * (((t |^ 1) * t) * t)))

      .= ((((5 * t) + (16 * (t |^ 5))) - (12 * (t |^ 3))) - (8 * ((t |^ (1 + 1)) * t))) by NEWTON: 6

      .= ((((5 * t) + (16 * (t |^ 5))) - (12 * (t |^ 3))) - (8 * (t |^ (2 + 1)))) by NEWTON: 6

      .= (((5 * t) - (20 * (t |^ 3))) + (16 * (t |^ 5)))

      .= (((5 * ( cosh x)) - (20 * (t |^ 3))) + (16 * (t |^ 5))) by SIN_COS2:def 4

      .= (((5 * ( cosh x)) - (20 * (( cosh x) |^ 3))) + (16 * (t |^ 5))) by SIN_COS2:def 4

      .= (((5 * ( cosh x)) - (20 * (( cosh x) |^ 3))) + (16 * (( cosh x) |^ 5))) by SIN_COS2:def 4;

      hence thesis;

    end;