# A to Z of Excel Functions: The ATAN2 Function

9 September 2016

*Welcome back to our regular A to Z of Excel Functions blog. Today we look at the ATAN2 function.*

**The ATAN2 function**

You see that bronzed figure on the beach and you think, maybe I should get **ATAN2**.** **Yes, this function returns the arctangent, or inverse tangent, of the specified **x**- and **y**-coordinates. The arctangent is the angle from the **x**-axis to a line containing the origin (0, 0) and a point with coordinates **(x_num, y_num). **The angle is given in radians between - π and π, excluding - π.

The **ATAN2 **function employs the following syntax to operate:

**ATAN2(x_num, y_num)**

The **ATAN2** has the following arguments:

**x_num:**this is required and represents the**x**-coordinate of the point**y_num:**this is also required and represents the**y**-coordinate of the point.

It should be further noted that:

- A positive result represents an anti-clockwise angle from the
**x**-axis; a negative result represents a clockwise angle **ATAN2(a,b)**equals**ATAN(b/a)**, except that**a**can equal 0 in**ATAN2**- If both
**x_num**and**y_num**are 0,**ATAN2**returns the*#DIV/0!*error value - To express the arctangent in degrees, multiply the result by
**180/PI( )**or use the**DEGREES**function.

Please see my example below:

*We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every other business day.*