A sector of a circle has a central angle of 100 degrees. If the area of the sector is 50pi, what is the radius of the circle?
Sector area = pi *r^2 ( 100 / 360)
50pi = pi * r^2 * ( 5/18) divide out pi
50 (18/5) = r^2
180 = r^2
r = sqrt 180 = sqrt (9 * 20) = 3sqrt (20)