Question

# If the lateral surface a cylinder is 94.2 cm 2 and its height is 5 cm, then findI. Radius of its base andII. Its volume

Hint: Compute radius from lateral surface area, proceed to find volume using the same radius.

Given, h= 5 cm
Let the radius be r cm, Now
(i) We know, Lateral/Curved Surface area=$2\pi rh$
Substituting all the values , we have
$\Rightarrow 94.2c{m^2} = 2\pi rh \\ \Rightarrow 94.2c{m^2} = 2 \times 3.14 \times r \times 5cm \\ \Rightarrow r = 3cm \\$

(ii) We know, Volume of cylinder= $\pi {r^2}h$
Substituting all the values along with value of r we found , we will have
$\Rightarrow \pi {r^2}h = 3.14 \times 3 \times 3 \times 5 \\ = 141.2c{m^3} \\$

Note: Formula of curved and total surface area, volume of general figures must be known for such
similar problems.