Question:
The curved surface area of a cylinder is 1320 cm2 and its base has diameter 21 cm. Find the height of the cylinder.
Solution:
Let $h$ be the height of the cylinder.
Given :
Curved surface area, $S=1320 \mathrm{~cm}^{2}$
Diameter, $d=21 \mathrm{~cm}$
Radius, $r=10.5$
$\mathrm{S}=2 \pi r h$
$1320=2 \pi \times 10.5 \times h$
$h=\frac{1320}{2 \pi \times 10.5}$
$h=20 \mathrm{~cm}$