## Summary

The Excel TAN function returns the tangent of angle given in radians. To supply an angle to TAN in degrees, multiply the angle by PI()/180 or use the RADIANS function to convert to radians.

## Purpose

Get the tangent of an angle

## Return value

The tangent value.

## Arguments

• number - The angle in radians for which you want the tangent.

=TAN(number)

## How to use

The TAN function returns the tangent of an angle provided in radians. In geometric terms, the tangent of an angle returns the ratio of a right-triangle's opposite side over its adjacent side. For example, the tangent of PI()/4 (45°) returns the ratio of 1.0.

``````=TAN(PI()/4) // Returns 1.0
``````

### Using Degrees

To supply an angle to TAN in degrees, multiply the angle by PI()/180 or use the RADIANS function to convert to radians. For example, to get the TAN of 60 degrees, you can use either formula below:

``````=TAN(60*PI()/180)
``````

### Explanation The graph of the tangent function, shown above, visualizes the output of the function for angles from 0 to a full rotation corresponding to the range [0, 2π]. The function has two vertical asymptotes within the range  [0, 2π] where the output diverges to infinity. The tangent function can be equivalently defined in terms of SIN and COS:

``````=TAN(θ) = SIN(θ)/COS(θ)
```
``` Author ### Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.