For reference, one full circle is 360 degrees or 2pi radians.
If we were to convert 360 degrees to radians, we could set up the following equation:
360k = 2pi
where k is a constant. By solving for k, we can find what value we must multiply any angle in degrees by to get its radian counterpart.
Divide both sides by 360:
k = 2pi/360
Reduce:
k = pi/180
So to convert an angle from degrees to radians, multiply it by pi/180. For example, 120 degrees would be:
120 * pi/180 = 2pi/3 radians
