Question

In the figure, you see the frame of a lampshade. It is to be covered with a decorative cloth. The frame has a base diameter of 20 cm and height of 30 cm. A margin of 2.5 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.

Answer 1

Here, r = 20/ 2 cm = 10 cm 

Height = 30 cm 

Circumference of the base of the 

frame = 2πr 

= 2π × 10 cm = 20π cm 

Height of the frame = 30 cm 

Height of the cloth needed for covering the frame 

(including the margin) = (30 + 2.5 + 2.5) cm = 35 cm 

Also, breadth of the cloth = circumference of the base of the frame. 

∴ Area of the cloth required for covering the lampshade = length × breadth 

= 35 × 20π cm² = 35 × 20 × 22 7 cm² = 2200 cm² Ans.