Q : 10    In Fig. \small 13.12, you see the frame of a lampshade. It is to be covered with a decorative cloth. The frame has a base diameter of \small 20\hspace{1mm}cm and height of \small 30\hspace{1mm}cm. A margin of \small 2.5\hspace{1mm}cm 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.


Answers (1)
N Nehul

Given, a cylindrical lampshade

Daimeter of the base = d = 20\ cm

Height of the cylinder  = 30\ cm

Total height of lampshade= (30+ 2.5 + 2.5) = 35\ cm 

We know, 

Curved surface area of a cylinder of radius r and height  h = 2\pi r h

Now, Cloth required for covering the lampshade = Curved surface area of the cylinder

\\ = 2\times\frac{22}{7} \times10 \times 35 \\ \\ = 22\times10\times10 = 2200\ cm^2

Therefore, 2200\ cm^2 cloth will be required for covering the lampshade.