The figure shows the frame of a lampshade. The diameter of the frame is 28 cm and its height is 18 cm. A margin of 1 cm is to be given for folding it over the top and 1 cm for bottom of the frame and a margin of 1 cm is to be provided for stitching its side (height). Find how much cloth is required for covering the lampshade ??
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Answer:
Diameter of the base of lampshade, d = 20 cm
radius r =
2
d
=
2
20
cm ;
height = 30 cm
Margin over the top and bottom = 2.5 cm + 2.5 cm = 5 cm
Hence total length of the cloth used
h = 30 cm + 5 cm
h = 35 cm
The cloth required for covering the lampshade = 2πrh = 2 X
7
22
X 10 X 35 = 2200 cm
2