number!Returns the arccosine of a number, in radians in the range 0 to Pi. The arccosine is the angle whose cosine is Number!is ...

!number!!Returns the arccosine of a number, in radians in the range 0 to Pi. The arccosine is the angle whose cosine is Number!is the cosine of the angle you want and must be from -1 to 1!