===== Acos =====
==== Format ====
**acos** ( //expression// )
==== Description ====
Computes the arc-cosine of //expression//.Angles are expressed in radians (0 to 2pi). 
 
==== See Also ====
[[asin|Asin]], [[atan|Atan]], [[cos|Cos]], [[degrees|Degrees]], [[radians|Radians]], [[sin|Sin]], [[tan|Tan]]