Dr. Neal G. answered 08/16/15
Tutor
5
(3)
Princeton Ph.D. retired engineering professor
There are 360 degrees in a circle. The reason for this has been lost in history
There are 2pi radians in a circle. The same angle can be measured in either degrees or radians. If the angle measure in degrees in D and the same angle measured in radians is R. Then the fraction of a circle represented by the angle is the same in either case. so
D/360 = R/(2pi)
or
D = 360(R/(2pi)) or R = (D*(2pi))/360.