Two stacks of 23 quarters each are shown One stack forms a cylinder but the other stack does not form a cylinder Stack 1 Stack 2 Why are the volumes of these two stacks of quarters equal Use Cavalieri s Principle to explain your thinking Every cross section perpendicular to the bases has an equal area Because both stacks have height the stacks must have the same volume If Stack 1 was twisted it would look like Stack 2 so the stacks must have the same volume If Stack 2 was straightened it would look like Stack 1 so the stacks must have the same volume Every cross section parallel to the bases has an equal area Because the stacks are the same height the stacks must have the same volume