if a meteor hits the earth and forms a crater that measures 10 miles in diameter, what is the area of the crater formed?

I guess they just want 

\(A = \pi r^2 = \pi \left(\dfrac{D}{2}\right)^2 \\ D=10 \Rightarrow A = \pi(5)^2 = 25\pi \approx 78.5\)