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# ATAN function

This article describes the formula syntax and usage of the ATAN function in Microsoft Excel.

## Description

Returns the arctangent, or inverse tangent, of a number. The arctangent is the angle whose tangent is number. The returned angle is given in radians in the range -pi/2 to pi/2.

## Syntax

ATAN(number)

The ATAN function syntax has the following arguments:

• Number    Required. The tangent of the angle you want.

## Remark

To express the arctangent in degrees, multiply the result by 180/PI( ) or use the DEGREES function.

## Example

Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.

 Formula Description Result =ATAN(1) Arctangent of 1 in radians, pi/4 0.785398163 =ATAN(1)*180/PI() Arctangent of 1 in degrees 45 =DEGREES(ATAN(1)) Arctangent of 1 in degrees 45

Applies To: Excel 2016, Excel 2010, Excel Starter, Excel 2013, Excel Online, Excel 2016 for Mac, Excel for Mac 2011, Excel 2007

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