Answer:
81pi mm^2
Step-by-step explanation:
The radius is 1/2 the diameter, and is used in finding the area of a circle.
The formula for this is
A = pi(r)^2
So the formula you would use is
A = pi (9)^2
= 81pi
Usually teachers accept it in terms of pi, but if not, you can use 3.14 and multiple it.
I hope this helped!
