Question

In the figure, you see the frame of a lampside. It is to be covered with a decorative cloth. The frame has a base diameter of $20cm$ and height of $30cm$. A margin of $2.5cm$ is to be given for folding it over the top and bottom of the frame. Find how much cloth is required for covering the lampshade.

Answer 1

Since, the cloth in the form of cylinder.

$\Rightarrow$Height, $H=2.5+30+2.5=35$cm (It includes margin)

Radius, $R=\frac{20}{10}=10$cm

$\Rightarrow$Cloth required $=2\pi rh$ (CSA of cylinder)

$=(2\times \frac{22}{7}\times 10\times 35)$cm${}^2$

$=2200$cm${}^2$