Question

Find volume and surface area of ball of diameter 21 cm

Answer 1

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We know that,

A ball is a sphere, so

Volume of a sphere=4/3πr³

Here, r=d/2=21/2 cm

=4/3×22/7×21/2×21/2×21/2

=11×21×21

=4851 cm³

Now, surface area=4πr²

=4×22/7×21/2×21/2

=22×3×21

=1386 cm²