A solid cylinder of radius and height is placed over other cylinder of same height and radius. The total surface area of the shape so formed is 4π rh+ 4πr2 .

False

As one cylinder is placed over another, so the base of first cylinder and top of other cylinder will not be covered in total surface area.


So,


Total surface area of shape formed = 2(Total surface of single cylinder) - 2(Area of base of cylinder)


= 2(2πrh + 2πr2) - 2(πr2)


= 4πrh + 2πr2


[As Total surface area of cylinder = 2πrh + 2πr2h, where r = base radius and h = height]


2