Trigonometry

<math.h>, <complex.h> and <tgmath.h> declare 50 functions for trigonometric computations.

Trigonometric functions
Name	Description		Source	Availability
`sin()`	Compute sine	(·)	`<math.h>`	C89	C90	C95	C99	C11
`cos()`	Compute tangent	(·)	`<math.h>`	C89	C90	C95	C99	C11
`tan()`	Compute tangent	(·)	`<math.h>`	C89	C90	C95	C99	C11
`atan2()`	Compute arc tangent	(·)	`<math.h>`	C89	C90	C95	C99	C11