# Radian

A radian ($rad$) is the angle ($\theta$) which subtends an arc equal to the length of the radius of a circle and the SI unit of angles. The angle of a circle is $2\pi$ radians.

## Convert Between Radians and Degrees

Given there are $360\degree$ in a circle and $2\pi\ rad$ in a circle, we can say $360\degree = 2\pi\ rad$.

You can solve for either side of the equation to determine the formula for conversion.

First, simplify:

$180\degree = \pi\ rad$

## Video: Intro to Radians

## Resources to Learn About Radians

## Deeper Knowledge on Radian

### Angular Motion

The basics of angular motion

## Broader Topics Related to Radian

### Circles (Geometry)

The mathematics of circles

### Math

Fun with numbers