Portions of Circles - Arc Measurements
30 degrees - 1/12 of the circle
45 degrees - 1/8 of the circle
60 degrees - 1/6 of the circle
90 degrees - 1/4 of the circle
120 degrees - 1/3 of the circle
180 degrees - 1/2 of the circle
270 degrees - 3/4 of the circle
