MS Excel: ATan Function
In Excel, the ATan function returns the arctangent (in radians) of a number.
The syntax for the ATan function is:
ATan( number )
number is the tangent of the angle that you wish to find.
Applies To:
- Excel 2007, Excel 2003, Excel XP, Excel 2000
For example:
Let's take a look at an example:

Based on the Excel spreadsheet above:
=ATan(A1) would return -0.674740942 =ATan(A2) would return 0 =ATan(A3) would return 1.522640814 =ATan(0.2) would return 0.19739556