C Language and Libraries Help (clang.hlp) (Table of Contents; Topic list)
Trigonometric Functions
 Description Example                     Up Contents Index Back
─────Run-Time Library───────────────────────────────────────────────────────
 
  Include:   <math.h>
 
  Syntax:    double cos( double x );
             double sin( double x );
             double tan( double x );
 
  Returns:   (cos) the cosine of <x> if successful, or 0 if not.
             (sin) the sine of <x> if successful, or 0 if not.
             (tan) the tangent of <x> if successful, or 0 if not.
             errno: ERANGE
 
  See also:  acos, cosh, _cosl, _matherr
                                    -♦-