Question

The diameter of a tennis ball is about 7 cm. How much metal is needed to make a can to hold three tennis balls? Include the top and bottom of the can. Round to the nearest square centimeter.

Answer 1

The three tennis balls will be staked up like this:

O
O
O

So how do you find the HEIGHT of the can? (if you are given only the DIAMETER of one ball?)

Answer 2

pir^2h

Answer 3

I don't really understand what to do...