What is a radian?

Here is a video about them. There is also more information below the video.

A radian is a unit of measuring angles just like a degree is. A radian is a distance on the circle’s circumference which is equal to 1 radius.

This means there are 2\pi radians in one circle or that 2\pi radians equals 360 degrees.

If 2\pi radians equals 360 degrees that means that 1 degree equals 2\pi divided by 360 radians or \pi divided by 180 radians.

1 radian = \frac{180}{\pi} degrees

1 degree = \frac{\pi}{180} radians


This is a degrees and radians chart. If 1 degree = \frac{\pi}{180}radians then 30 degrees equals 30 times that or \frac{\pi}{6} radians. The same thing can be done to find the radian measure for other angles.