The ATAN function in Excel calculates the arctan (inverse of Tan) of a given number and returns the angle in radians between 0 and π. Arctan is inverse of tan.

ARCTAN(**a/b)= **θ

Arctan of the opposite side – a, divided by the adjacent side – b equal to the angle θ.

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**Syntax of ATAN Function in Excel**

ATAN(number)

Where Argument number is a value between -1 and 1, which you need to calculate the arctan.

**Example of ATAN Function in Excel**

**Formula**

- From Row number 2 to 5 ATAN is calculated in radians for value between -1 and 1 that is being passed as input to the ATAN Function.
- In row number 6, ATAN is calculated in degree for the value 1 which is 45 degree

**Note: **if you want the value of ATAN Function to be calculated in degrees, then convert it in degrees using DEGREES Function as shown in 6^{th} row.