acos
 
 
 

Returns the radian value of the arc cosine of a number. The arc cosine is the angle whose cosine is the specified number. The returned value is from 0 to pi.

float acos(float number)

number is the cosine of the angle, and must be from -1 to 1.

Example

acos(1)

Returns 0.

acos(-0.5)

Returns 2.0944 radians.