ummm...
Well lets take an example.
Say you have the angle
and lets compare that with the angle.
.
.
So to get to the angle I would rotate all the way through radians (one around the circle so I am back where I started) then go radians.
Moral of the story.
I can go around any multiple of 2\pi radians as many times as I want and still end up in the same place.