How much more pizza do you get if you purchase a large pizza instead of a medium?

Question

A large pizza has a diameter of 10 square inches. A medium pizza has a diameter of 8 square inches. How much more pizza do you get if you purchase a large pizza instead of a medium? Round your answer to the nearest tenth of a square inch, if necessary.  

Answer 1

You need to find the difference of the area of the large pizza and the area of the small pizza.

The area of a circle can be found by A = πr²

The radius r is half of the diameter, thus the area of the large pizza is π5² = 25π in² and the area of the small pizza is π4² = 16π in². The difference is 9π in², which is approximately 28.3 in² to the nearest tenth of a square inch.