when food is packaged in cans, it is not necessary that the material in both ends and the side be the same cost. if the ends of the can cost E $/cm squared, the side costs S $/cm squared and the label (including glue to attach the label to the can) is L $/cm squared, show that the best shape (most economical) to build the can is when r= (S+L)h/2E, where r is the radius of the can and h is its height.