Returns the arccosine of a number. The arccosine is the angle whose cosine is number. The returned angle is given in radians in the range 0 (zero) to p (pi).
Syntax
ACOS(number)
Number is the cosine of the angle you want and must be from -1 to 1.
If you want to convert the result from radians to degrees, multiply it by 180/PI().
Examples
ACOS(-0.5) equals 2.094395 (2p/3 radians)
ACOS(-0.5)*180/PI() equals 120 (degrees)