In a cylinder, if radius is doubled and height is halved, curved surface area will be
(a) halved (b) doubled
(c) same (d) foru times
Let radius of the first cylinder (r1) = r
and height (h1) = h
∴ Surface area = 2π rh
If radius is doubled and height is halved
then radius (r2) = 2r and height (h2)=h2
Then surface area = 2π(2r)×h2
=2π×2r×h2=2πrh
∴ Their surface area remains the same