The Excel ACOS function calculates the arccosine (i.e. the inverse cosine) of a given number, and returns an angle, in radians, between 0 and π.
The syntax of the function is:
Where the number argument is the value, between -1 and +1, for which you want to calculate the arccosine.
Converting from Radians to DegreesAn example of this is provided below.
Column A of the following spreadsheet the Excel Acos Function, used to calculate the arccosine of four different values.
Note that in cell A4 of the above spreadsheet, the Excel Degrees function is used to convert the calculated angle from radians to degrees.
Further details and examples of the Excel Acos function can be found on the Microsoft Office website.
If you get an error from the Excel Acos function, this is likely to be one of the following:
|#NUM!||-||Occurs if the supplied number argument is outside the range -1 to +1.|
|#VALUE!||-||Occurs if the supplied number argument is non-numeric.|