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Surface Areas and Volumes
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27/07/2021 11:16 am
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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. (Assume π = 22/7)
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27/07/2021 11:17 am
h = height of the frame of lampshade, looks like cylindrical shape
r = radius
Total height is h = (2.5 + 30 + 2.5) cm
= 35cm and
r = (20/2) cm = 10cm
Use curved surface area formula to find the cloth required for covering the lampshade which is 2πrh
= (2 × (22/7) × 10 × 35) cm2
= 2200 cm2
Hence, 2200 cm2 cloth is required for covering the lampshade.