Question

The surface area of a sphere is same as the curved surface area of a right circular cylinder whose height and diameter are $12cm$ each. The radius of the sphere is:

• A. $3cm$
• B. $4cm$
• C. $6cm$
• D. $12cm$

Answer 1

Answer: (C)

$6cm$

Let, $R$ is the radius of the sphere, $r$ is the radius of the cylinder and $h$ is the height of the cylinder.

Since, surface area of sphere is same as the curved surface area of cylinder.

Therefore,

$4\pi r^2=2\pi Rh$

$2r^2=6\times 12$

$r^2=36$

$r=6cm$