Futurebasic/Language/Reference/acos

Function
✔ Appearance ✔ Standard ✔ Console

Syntax
radianAngle# = ACOS (expr)

Description
Returns the arccosine of  in radians. In other words, if  represents the cosine of some angle, then   returns the angle. The returned angle will be in the range of 0 to π radians (which corresponds to 0 to 180 degrees). always returns a double-precision result.