The shorter edges of a 44cm x 25cm metal sheet are joined to form the curve surface of a cylinder. What is the volume of the cylinder? What is the area of metal sheet required to make the top and the bottom cylinder?
h = 25
2 pi r = 44
so r = 22/pi
pi r^2 h = V = pi (22/pi)^2 (25)
area top = pi r^2
area bottom = pi r^2
so
area needed = 2 pi r^2 = 2 pi (22/pi)^2
Now of course sheets of metal usually come rectangular, not circular, so in real life some will get wasted.