# What is the radian measure of a right angle?

##### 2 Answers

#### Explanation:

Radians are a unit measure for angles defined as the ratio between the lenght of an arc of circumference and the radius of the circumference itself.

This image from wikipedia explains it quite well:

and this gif helps you understainding why an angle of

That being said, we only need to use some proportions: since a right angle measures

We have a very goofy system where our circle constant **half** a circle,