Use the correct formula to find the area of a circle if the diameter is 21 mi. Round to the nearest hundredths place.
The formula to find the area of a circle is A = πr², where r is the radius of the circle. Since the diameter is 21 mi, the radius is half of the diameter, which is 10.5 mi.
Now, substitute the radius into the formula:
A = π(10.5)²
A = π(110.25)
A ≈ 346.36 mi²
Therefore, the area of the circle is approximately 346.36 square miles.