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प्रश्न
Find the volume and surface area of a sphere of diameter 21 cm.
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उत्तर
Diameter of sphere = 21 cm
∴ Radius of sphere = `21/2` cm
∴ Surface area of sphere = 4πr2
= `4 xx 22/7 xx 21/2 xx 21/2`
= 1386 cm2
Volume of sphere = `4/3`πr3
= `4 xx 22/7 xx 21/2 xx 21/2 xx 21/2`
= 4851 cm3.
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