Return arc cosine of a number

Contract
Return type	wob
No input parameters.

Water Contract
<method number.double.acos/>

See also: cos, cosh, sin, asin, sinh, tan, atan, tanh, atan2, radians_to_degrees, degrees_to_radians, double

Returns the arc cosine of a _subject of type double . May be used to convert a cosine value back into an angular measure in radians.

45.<degrees_to_radians />.<cos />

0.7071067811865476

0.7071067811865476.<acos />.<radians_to_degrees />

45.0