ACOS function
This article describes the formula syntax and usage of the ACOSfunction in Microsoft Excel.
Description
Returns the arccosine, or inverse cosine, of a number. The arccosine is the angle whose cosine is number. The returned angle is given in radians in the range 0 (zero) to pi.
Syntax
ACOS(number)
The ACOS function syntax has the following arguments:

Number Required. The cosine of the angle you want and must be from 1 to 1.
Remark
If you want to convert the result from radians to degrees, multiply it by 180/PI() or use the DEGREES function.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How do I copy an example?

Select the example in this article.
Important Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In Excel, create a blank workbook or worksheet.

In the worksheet, select cell A1, and press CTRL+V.
Important For the example to work properly, you must paste it into cell A1 of the worksheet.

To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
After you copy the example to a blank worksheet, you can adapt it to suit your needs.

