In constructing a can with a volume of in the shape of a right circular cylinder, no wa...

In constructing a can with a volume of in the shape of a right circular cylinder, no waste is produced when the side of the can is cut, but the top and bottom are each stamped from a square sheet and the remainder is wasted as shown in the figure.

a. Express the area of the material used when stamping the top and bottom as a function of the radius r

b. Approximate the dimensions of the can that uses the least amount of material with this construction method.