Question

In a cylinder, radius is doubled and height is halved, curved surface area will be. (A) halved (B) doubled (C) same (D) four times​

Answer 1

Answer :-

(C) Same

Explanation:-

Curved surface area of cylinder is 2πrh

According to question,

➤ Radius = Doubled (2r)

➤ Height = Halved (H/2)

According to formula,

➨ 2πrh = 2π(2r)(H/2)

➨ 2πrh = 2πrh

Hence, Proved

Answer 2

Option C

Same

Curved surface area of cylinder is 2πrh.

Given, 

$R=2r,H=2h$

Therefore, curved surface area of the cylinder

$=2πRH$

$=2π(2r)(2h)$

$=2πrh$