Excel Function : ACOS
Math and trigonometry
Returns the arccosine of a number
Microsoft Excel Reference Page
Syntax and Description of the ACOS Excel Function
The syntax for the ACOS function in Microsoft Excel is: =ACOS(number) Where "number" is the number for which you want to find the arc cosine.
About ACOS Excel Function
The ACOS function returns the arccosine, or inverse cosine, of a number. The number must be between -1 and 1.