Converting Degrees to Radians:

The conversion of degrees to radians is just a proportion problem.
ex.
Convert 60° to radians.

60/360 = X/2p
2p (60) = 360x
2(3.14)(60) = 360x
1.0467 = x
60° = 1.0467 rads

If P is a point on the initial side of angle q, let P be r units from the vertex, as the initial side of angle q is rotated to the terminal side, and P traces an arc length s then:

From now on, q = s will be understood to be in radians, except in places where "rad" is needed for clarity.