Thread: how to compute tan?

  1. #1
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    May 2003
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    how to compute tan?

    can somebody please help me with this problem?

    Given the function f(x) : 2tanx-x-1=0, write a program that will compute the value for x using trial and error.

    Let me explain again, the user inputs a value for x and substitutes it in the formula above. The left side of the equation should equal to 0 once it's computed. If the x entered does not satisfy the equation, then the program should output the correct value for x. My problem is, I can't figure out how to do the tangent in the formula and I can't even find out what x should be.

    I'm thinking of placing my code here but I think it's useless anyway cos it's all wrong. I'm using MS Visual C++ to write the code. please help... >_<

    wait! i'm not asking you to write the whole program for me but i just want to know how to calculate formulas with tangents in it like the one above. thank you!

  2. #2
    It's full of stars adrianxw's Avatar
    Join Date
    Aug 2001
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    4,829
    Code:
    #include <math.h>
    #include <stdio.h>
    
    void main( void )
    {
       double pi = 3.1415926535;
       double x, y;
    
       x = tan( pi / 4 );
       y = tanh( x );
       printf( "tan( %f ) = %f\n", pi/4, x );
       printf( "tanh( %f ) = %f\n", x, y );
    }
    ... from MSDN.
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