The area of a circle with radius r is calculated using the formula below.
A=π r^2We know the diameter is 16 feet, and that the diameter of a circle is exactly twice as long as its radius. With that information we can calculate the radius.
2r = D
2r = 16
r = 8
The radius of the circle is 8 feet. By substituting 8 for r in the formula, we can calculate A.
