Calculate the area of a circle with a diameter of 18 m. Give an exact answer.
The radius of the circle is half of the diameter, so the radius is 18/2 = 9 meters.
The formula for the area of a circle is A = πr^2, where r is the radius.
Substitute the radius into the formula to get:
A = π(9)^2
A = π(81)
A = 81π
Therefore, the area of the circle is 81π square meters.