#include <math.h>float sinf(float arg);double sin(double arg); long double sinl(long double arg);
sinf( ) and sinl( ) were added by C99.
The sin( ) family of functions returns the sine of arg. The value of arg must be in radians.
Related functions are asin( ), acos( ), atan2( ), atan( ), tan( ), cos( ), sinh( ), cosh( ), and tanh( ).