2. But if you go to your cupboard or grocery store with a ruler, you will discover that the height is usually greater than the diameter and the ratio h/r varies from 2 up to 3.8. Let's see if we can explain this phenomenon. The material for the cans is cut from sheets of metal. The cylindrical sides are formed by bending rectangles; these rectangles are cut from the sheet with little or no waste. But if the top and bottom discs are cut from squares of side 21", this leaves considerable waste material, which may be recycled but has little or no value to the can makers. If this is the case, show that the amount of metal used is minimized when h 8 \"T 71