How many square feet in a 10 foot diameter circle?

To find the area of a circle, you use the formula A = πr^2, where r is the radius of the circle. Since the diameter is 10 feet, the radius would be half of that, which is 5 feet. Plugging this into the formula, we get A = π(5)^2 = 25π square feet. This is approximately 78.54 square feet.