#include <math.h>
double sin(double x);
sin returns the radian circular sine of x.
If |x| > 10^9, errno is set to EDOM and sin returns HUGE_VAL.
sin returns x if x is NaN.
sin returns NaN with invalid signal if |x| is ∞.
sin conforms to ISO/IEC 9899:1990 (C90) and ISO/IEC 9899:1999 (C99).