A circle is centered at O. Find the radius of the circle.
Dude.. they already told you the area of a circle...πr^2. If you know that the area is 9πft^2, then r = ___ft.
Hint: 3^2 = 9.
The problem gave you the area \(9\pi\)\(ft^2\), I think you could figure it out from there.
