Answer: 20.25pi square cm
==============================================
Work Shown:
C = 2pi*r
9pi = 2pi*r
r = (9pi)/(2pi)
r = 4.5
A = pi*r^2
A = pi*(4.5)^2
A = 20.25pi square cm
------------------
Step-by-step explanation:
The first portion involves using the circumference C = 9pi to determine the radius r. The circumference is the perimeter around the circle.
Once we know that r = 4.5 cm, we then plug that into the area of a circle formula A = pi*r^2
Side notes: