# Mark the correct alternative in each of the following: In a cylinder, if radius is doubled and height is halved, curved surface area will be - Mathematics

MCQ

Mark the correct alternative in each of the following:
In a cylinder, if radius is doubled and height is halved, curved surface area will be

• halved

• doubled

• same

• four times

#### Solution

Let S1 be the curved surface area of the cylinder with radius r1 and height h1, then

S_1 = 2pir_1h_1……. (1)

Now, let S2 be the surface area after changing the dimension, then

r_2 = 2r_1,h_2=h_1/2

So,

S_2 = 2pir_2h_2 = 2pi xx 2r_1xxh_1/2

⇒ S_2 = 2pir_1h_1 = S_1

Concept: Surface Area of Cylinder
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#### APPEARS IN

RD Sharma Mathematics for Class 9
Chapter 19 Surface Areas and Volume of a Circular Cylinder
Exercise 19.4 | Q 1 | Page 28

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