The Excel ATAN Function

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Arctangent

The Arctangent is the inverse of the tangent.

Therefore, for the simple right-angled triangle below, the arctangent of the opposite side, o, divided by the adjacent side, a, is equal to the angle θ.

i.e. for the triangle above,

The Inverse trig. functions are discussed further on the Wikipedia Inverse Trigonometric Functions Page

Related Functions:

ACOS Function

ASIN Function

TAN Function

Basic Description

The Excel ATAN function calculates the arctangent (ie. the inverse tangent) of a given number, and returns an angle, in radians, between -π/2 and +π/2.

The format of the function is :

ATAN( Number )

Where the Number argument is the value, for which you want to calculate the arctangent.

Converting from Radians to Degrees

If you want the angle returned by the Atan function to be expressed in degrees, you can convert it, using the Excel Degrees function :

=DEGREES( Radians )

An example of this is included below.

Example

Column A of the spreadsheet below, shows examples of the Excel Atan Function, used to calculate the arctangent of different values. In the example in cell A4, the result is converted from radians, into degrees.

The formulas are shown in the spreadsheet on the left and the results are shown in the spreadsheet on the right.

Formulas