# ATAN2 function: Description, Usage, Syntax, Examples and Explanation

## What is ATAN2 function in Excel?

ATAN2 function is one of the Math and Trig functions in Microsoft Excel that 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 -pi and pi, excluding -pi.

## Syntax of ATAN2 function

ATAN2(x_num, y_num)

The ATAN2 function syntax has the following arguments:

**X_num:**The x-coordinate of the point.**Y_num:**The y-coordinate of the point.

## ATAN2 formula explanation

- A positive result represents a counterclockwise 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.

## Example of ATAN2 function

Steps to follow:

1. Open a new Excel worksheet.

2. Copy data in the following table below and paste it in cell A1

Note: For formulas to show results, select them, press F2 key on your keyboard and then press Enter.

You can adjust the column widths to see all the data, if need be.

Formula |
Description |
Result |

=ATAN2(1, 1) | Arctangent of the point 1,1 in radians, pi/4 | 0.785398163 |

=ATAN2(-1, -1) | Arctangent of the point -1,-1 in radians, -3*pi/4 | -2.35619449 |

=ATAN2(-1, -1)*180/PI() | Arctangent of the point 1,1 in degrees | -135 |

=DEGREES(ATAN2(-1, -1)) | Arctangent of the point 1,1 in degrees | -135 |