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Question
Find the surface area of a sphere of diameter 21 cm.
`["Assume "pi=22/7]`
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Solution
Radius (r) of sphere = `"Diameter"/2`
= `(21/2) cm`
= 10.5 cm
Surface area of sphere = 4πr2
= `[4xx22/7xx(10.5)^2] cm^2`
= 1386 cm2
Therefore, the surface area of a sphere having diameter 21 cm is 1386 cm2.
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