Next time you hear someone complain about never using the math you learned in school in real life, remember this question.
You’d think the two smaller pies would have more, but that would be wrong. You just need some pi with your pizza.
Remember the formula? A = irR2. The “pi R squared” thing works in this case even though the pies are round.
The area of a circle is the same as half the diameter (5 inches for the ten-inch and 3.5 inches for the seven-inch) multiplied by itself (25 and 12.25) times 3.1417 (pi).
So a ten-inch pizza is the better deal. It has about 78.5 square inches of cheesy goodness, while two seven-inch pizzas have only about 77.