Math problem

May 25, 2014 at 9:54pm
Hi,

my problem is this:

double st;

st = 100 * sin(360 * (10000/23));

Now when my calculator is working in radians st is evaluated to 97% which is the value I'm after. When working in degrees it is approx -75% which is wrong. In Netbeans st is -75% like the wrong calculator value. How can I get 97% in Netbeans using the above formula?

What's wrong?

Any help appreciated.

FC.
May 25, 2014 at 10:11pm
I'm pretty sure the standard(?) has all the trigonomic functions using radians. However, if need be, you can convert from radians to degrees and vice versa:

rad = deg*pi/180
deg = rad*180/pi
Last edited on May 25, 2014 at 10:16pm
May 25, 2014 at 10:16pm
Here's the example from the tutorial.
http://www.cplusplus.com/reference/cmath/sin/

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/* sin example */
#include <stdio.h>      /* printf */
#include <math.h>       /* sin */

#define PI 3.14159265

int main ()
{
  double param, result;
  param = 30.0;
  result = sin (param*PI/180);
  printf ("The sine of %f degrees is %f.\n", param, result );
  return 0;
}


Using pi/180 instead of 360 in your example gave me a result of 96.1262.
Last edited on May 25, 2014 at 10:16pm
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