Answer:
448π cubic feet.
Explanation:
The volume of a cone can be calculated using the formula V = (1/3)πr^2h, where r is the radius of the base and h is the height of the cone. Since the diameter of the cone is 16 feet, the radius is 8 feet. Therefore, the volume of the cone is (1/3)π(8 feet)^2(21 feet) = 448π cubic feet.