Question:
The curved surface area of a cylindrical road is 132 cm2. Find its length if the radius is 0.35 cm.
Solution:
Consider $h$ to be the height of the cylindrical rod.
Given:
Radius, $r=0.35 \mathrm{~cm}$
Curved surface area $=132 \mathrm{~cm}^{2}$
We know :
Curved surface area $=2 \times \pi \times \mathrm{r} \times \mathrm{h}$
$132=2 \times \frac{22}{7} \times 0.35 \times \mathrm{h}$
$h=\frac{132 \times 7}{2 \times 22 \times 0.35}$
$h=60$
Therefore, the length of the cylindrical rod is $60 \mathrm{~cm}$.