On this page is a *cosine calculator*, for either angles or degrees. Enter an angle's measurement, choose the units, and run the calculator to see the cosine.

## Cosine Calculator for Angles or Radians

**Table of Contents**show ▼

## Using the Cosine Calculator

To use the tool to find the cosine, enter the measurement of the angle in either degrees or radians, choose the units, and compute.

**Angle**- measurement of the angle (in degrees or radians)**Degrees or Radians?**- use the menu to choose the units

Once you're happy with the inputs, click the "Compute Cosine" button.

**Cosine**- the cosine, or ratio of the adjacent side over the hypotenuse

## What is the cosine?

For a given angle in a right triangle, cosine is the ratio of the adjacent side to the longest side, or hypotenuse.

Since the hypotenuse is longest, the adjacent side can be – at max – equal to the hypotenuse. It follows that cosine is always less than or equal to 1.

Beyond triangles, trigonometric functions can be used to find the ratio between sides of a unit circle – a circle with radius 1.

### Cosine as a formula

As a trigonometry formula, cosine is usually abbreviated as "cos", as in the following equation:

\cos(\theta)

If you know the result of the cosine function, you can use arccos or the inversecosine to find the angle.

*After, find all the trigonometric functions and inverse trigonometric functions in one tool.*