Question

The height of a right circular cylinder is $6m$. If three times the sum of the areas of its two circular faces is twice the area of the curved surface, then the radius of the base is

• A. $4m$
• B. $3m$
• C. $2m$
• D. $1m$

Answer 1

Answer: (A)

$4m$

Let the radius of the cylinder be $r$.
Area of the circular face $=\pi r^2$
Curved Surface Area of a Cylinder $=2\pi rh$
Given, three times the sum of the areas of its two circular faces is twice the area of the curved surface
$\Rightarrow 3(\pi r^2+\pi r^2)=2(2\pi r\times 6)$
$\Rightarrow 6\pi r^2=24\pi r$
$\Rightarrow r=4m$