<function name="acos" parent="math" type="libraryfunc"> <description>Returns the of the given number.</description> <description>Returns the [arccosine](https://en.wikipedia.org/wiki/Arccosine) of the given number.</description> <realm>Shared and Menu</realm> <args> <arg name="cos" type="number">Cosine value in range of -1 to 1.</arg> </args> <rets> <ret name="" type="number">An angle in radians, between 0 and pi, which has the given cos value. <page>nan</page> if the argument is out of range.</ret> </rets> </function>