Pizza House sells 2 different pizza sizes: A 16-inch-diameter pizza and a 12-inch-diameter pizza. How much more pizza do you get by ordering the 16 in. diameter than the smaller one

The 16 inch diameter leads to a 8 inch radius (cut the diameter in half). So r = 8 is plugged into the area of a circle formula to get

A = pi*r^2

A = pi*8^2

A = pi*64

A = 64pi ... which is the exact area in terms of pi

We'll use this value later, so let's call it A1 = 64pi

Repeat for the other pizza. We have a 12 inch diameter mean the radius is r = 6 so its area would be ...

A = pi*r^2

A = pi*6^2

A = pi*36

A = 36pi

We'll use this value later, so let's call it A2 = 36pi

Now subtract the two areas (large - small) to get the difference in areas which we'll call D

D = A1 - A2

D = 64pi - 36pi

D = (64-36) pi

D = 28pi

The difference in the two areas is exactly 28pi square inches

Now use a calculator to find that 28*pi = 28*3.1415926535898 = 87.964594 approximately if you were to round to 6 decimal places

Approximate answer: 87.964594 square inches

note: I went with the approximate answer because it's probably easier to visualize a fractional or decimal part of a pizza better than some number in terms of pi