CCC Common Core Pre-Test Practice

The area of a circle is found using A = π r^2. With a radius of 9, plug in: A = π × 9^2 = π × 81 = 81π. So the area is 81π square units. The other values correspond to circles with radii not equal to 9 (for example, 72π would come from a radius about 8.49, 63π from about 7.94, and 90π from about 9.49), so they aren’t correct for this radius.