Question

Find the surface area of a sphere of radius 21 cm​

Answer 1

Step-by-step explanation:

r=21cm

surface area of a sphere=4πr

=4×22/7×21

=4×22×3

=264cm²

hope it help you......☺️

Answer 2

✠Given

• Radius = 21 cm.

✠To Find

• Surface Area = ?

✠Solution

Formula Used :

• ${\boxed{ \pmb{\sf{Surface \:area_{(Sphere)} = 4\pi{r}^{2}}}}}$

♧︎︎︎Finding the surface area of sphere :

${\implies{\sf{Surface \:area_{(Sphere)} = 4\pi{r}^{2}}}}$

${\implies{\sf{Surface \: area_{(Sphere)} = 4 \times \dfrac{22}{7} \times {(21)}^{2}}}}$

${\implies{\sf{Surface \: area_{(Sphere)} = 4 \times \dfrac{22}{7} \times {(21\times 21)}}}}$

${\implies{\sf{Surface \: area_{(Sphere)} = 4 \times \dfrac{22}{7} \times 441}}}$

${\implies{\sf{Surface \: area_{(Sphere)} = 4 \times \dfrac{22}{\cancel{7}} \times \cancel{441}}}}$

${\implies{\sf{Surface \: area_{(Sphere)} = 4 \times 22 \times 63}}}$

${\implies{\sf{\red{Surface \: area_{(Sphere)} = 5544\: {cm}^{2}}}}}$

${ \qquad{ \underline{ \rule{500pt}{3pt}}}}$

Hence, the surface area of sphere is 1386 cm²

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