Since 360 degrees are equivalent to 2p radians, or 180 degrees are equivalent to p radians, it can be applied as a conversion factor to convert degree measure to radian measure, and vice versa.
So you multiply the degrees by Pi Radians/180 degrees.
To convert the other way, 180 degrees/ Pi Radians.
Example:
Express 225º in radians.
Answer:
255 deg x pi radians/180 deg
= 5 pi/4 radians