A ring shaped region is shown below. It's inner radius is 17 yd, and its outer radius is 22 yd. find the area of the shaded region.
22^2 pi - 17^2 pi = (484 - 289) * pi = 195 pi
A cool way to do 22^2-17^2 = (22+17)(22-17) = 39 * 5 = 195
:))
=^._.^=
when memorization is less efficient
+13 
