In a circle, a 135degrees sector has area 54pi in2. What is the radius of the circle?
+128408 We have that 135° = (3/4)pi rads
The area of the sector has the form
A = (1/2) r^2 ( theta in rads)
So
54 pi = (1/2) r^2 [ 3/4] pi divide out pi
54 = (1/2) (3/4) r^2
54 = (3/8) r^2 divide both sides by 3
18 = (1/8) r^2 multiply both sides by 8
144 = r^2 take the positive root
12 (in) = r
