Question

In Fig., 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

Diameter of cylindrical frame, d= 20 cm, 

∴ r = 10 cm. height, h = 30 cm. 

For folding 2.5 cm is required. 

∴ Total height = 30 + 2.5 + 2.5 = 35 cm. 

Curved surface area of cloth covered, A 

A= 2πrh

= 44 × 50 

= 2200 cm² .