Question

Find the volume of sphere of radius 21 cm
and also surface area​

Answer 1

TO FIND :

Volume of a sphere;

GIVEN:

Radius = 21 cm

$\frac{4}{3} \pi {r}^{3} \\ \frac{4}{3} \times \frac{22}{7} \times ({21cm})^{3} \\ when \: further \: solved \:it \: gives \: us \: 38808 {cm}^{3}$

Volume of the sphere is 38,808 cm³.

Surface area of a sphere;

$4\pi r {}^{2} \\ 4 \times \frac{22}{7} \times {(21cm)}^{2} \\ when \: further \: solved \: it \: gives \: us \: 5544 {cm}^{2}$

Surface area of the sphere is 5544cm².

HAVE A NICE DAY!!!

Answer 2

Given: Radius of a sphere is 21cm.

Need to find: Volume & surface area of the sphere?

⠀⠀━━━━━━━━━━━━━━━━━━━⠀

❍ Let's consider radius of the sphere as r.

⠀⠀⠀⠀⠀

As we know that,

⠀⠀⠀⠀⠀

$\begin{gathered}\star\:{\underline{\boxed{{\frak{Volume_{\:(Sphere)}}= \pi \times r^{3} \times \dfrac{4}{3}}}}}\\\\\\ \bf{\dag}\:{\underline{\frak{Putting\:given\:values\:in\:formula,}}}\\\\\\ :\implies\sf \dfrac{22}{7}\times {21}^{3} \times \dfrac{4}{3}\\\\\\ :\implies\sf \dfrac{22}{7}\times {21} \times 21 \times 21 \times \dfrac{4}{3}\\\\\\ :\implies\sf \dfrac{22}{7}\times {21} \times 21 \times 7 \times {4}\\\\\\ :\implies\sf {22}\times {21} \times 21 \times {4}\\\\\\ :\implies\sf {22}\times {21}^{2} \times {4}\\\\\\ :\implies\sf {22}\times 441\times {4} \\\\\\ :\implies{\underline{\boxed{\frak{\purple{38808 {cm}^{3} }}}}}\:\bigstar\\\\\end{gathered}$

⠀⠀━━━━━━━━━━━━━━━━━━━⠀

« Now, Finding surface area of the sphere,

→ 4πr²

→ 4 × 22/7 × (21)²

→ 4 × 22/7 × 21 × 21

→ 4 × 22 × 3 × 21

→ 5544 cm²

Therefore,

⠀⠀⠀⠀⠀

• Surface area of the sphere, 5544cm²
• Volume of the sphere, 38808cm³

⠀⠀⠀⠀⠀

$\therefore\:{\underline{\sf{Hence,\:Surface \: area \: and \: Volume \:of\:sphere\:is\:\bf{5544 {cm}^{2} } \: \sf { and } \: \bf{38808 \: {cm}^{3} } \: \sf{respectively}.}}}$