Familiarize yourself with circle angles. On a graphed plane with four quadrants, circle angles are split up into numerals with pi symbols. For example, 180 degree = pi while 360 degree = 2 pi.
Figure out the terminal point of the equation. The terminal point is the x and y coordinates of your circle angle. Take the angle and check the circle angle wheel to figure out what your terminal point is.
Calculate the reference number. The reference number equals pi -- the terminal point. For example, if your terminal point = 5 pi / 6, your reference number = pi / 6. Pi would equal 6 pi / 6, and 6 -- 5 = 1 or 1 pi / 6. Simplify 1 pi / 6 to pi / 6.