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Surface Areas and Volumes
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29/07/2021 11:11 am
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A right circular cylinder just encloses a sphere of radius r (see fig.). Find
(i) surface area of the sphere,
(ii) curved surface area of the cylinder,
(iii) ratio of the areas obtained in(i) and (ii).
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29/07/2021 11:12 am
(i) Surface area of sphere = 4πr2, where r is the radius of sphere
(ii) Height of cylinder, h = r + r =2r
Radius of cylinder = r
CSA of cylinder formula = 2πrh
= 2πr(2r) (using value of h)
= 4πr2
(iii) Ratio between areas = (Surface area of sphere)/CSA of Cylinder)
= 4r2/4r2 = 1/1
Ratio of the areas obtained in (i) and (ii) is 1:1.