Calculates the sine of an angle

#include <math.h>
double sin ( double x  );
double sinf ( float x  );         (C99)
double sinl ( long double x  );         (C99)

The sin( ) function calculates the sine of the angle represented by its argument x as a number of radians. The return value is in the range -1 sin(x) 1.

Example

#define DEG_PER_RAD ( 180.0 / PI )

const double PI = 4.0 * atan( 1.0 );
double a[4];

printf( "\nEnter an acute angle measure, in degrees: " );

if ( scanf( "%lf", a ) < 1 ||  ( a[0] <= 0 || a[0] >= 90 ) )
  printf( "\nThat's not an acute angle.\n" ), exit( 1 );
else
{
  a[1] = a[0] + 90 ;
  a[2] = 180 - a[0] ;
  a[3] = 225 + a[0] ;
  for ( int i = 0 ; i < 4 ; i ++ )
    printf( "The sine of %4.2lf degrees is %6.4lf.\n",
            a[i], sin( a[i] / DEG_PER_RAD ) );
}

See Also

cos( ), tan( ), asin( ), csin( )