Question

What is the exact area of a circle with a diameter of 18 feet?

A. 36π square feet

B. 81π square feet

C. 324π square feet

D. 1296π square feet

Answer 1

The formula for the area of a circle is


`\pi r^(2)`

We know the diameter, and the radius is half of the diameter. So the radius is 9. Now we plug that into the formula.


`\pi 9^(2) =81 \pi`

So the answer is B, 81 pi square feet