# Futurebasic/Language/Reference/acos

< Futurebasic | Language | Reference

## AcosEdit

### FunctionEdit

✔ Appearance ✔ Standard ✔ Console

### SyntaxEdit

radianAngle# = ACOS (expr)

### DescriptionEdit

Returns the arccosine of

in radians. In other words, if *expr*

represents the cosine of some angle, then *expr*`ACOS(`

returns the angle. The returned angle will be in the range of 0 to π radians (which corresponds to 0 to 180 degrees). *expr*)`ACOS`

always returns a double-precision result.

### NotesEdit

No special notes.