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Q : 2    Find the surface area of a sphere of diameter:

             (ii) 21 cm 

Answers (1)

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Given,

The diameter of the sphere = 21\ cm

We know,

The surface area of a sphere of radius r = 4\pi r^2

\therefore Required surface area = 4\times\frac{22}{7} \times\left (\frac{21}{2} \right )^2

= 4\times\frac{22}{7} \times\frac{21}{2}\times\frac{21}{2}

\\ = 22\times3\times21 \\ = 1386\ cm^2

Posted by

Nehul

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