Question

if radius of a cylinder is doubled and height is halved then its curved surface area will be

Answer 1

the curved surface area will be same as earlier...
as Curver surface area of cylinder = 2 π RH
new curved surface area = 2 π 2R 1/2H...
2 cancelled by each other...then the actual value will...be same

Answer 2

C.S.A of cylinder = 2πrh
           
if radius is doubled and height is halved then c.s.a = 2π*2r*h/2

csa = 2πrh 

then in both case csa is equal