Question

find the volume and surface area of sphere of radius 2.1cm​

Answer 1

Answer:

the volume of the sphere is 2.261 cm³

Answer 2

Given :-

• Radius of sphere is 2.1 cm

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To Find :-

• The volume and surface area of sphere

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Formulas Used :-

♣️ Surface Area Of Sphere :

$\bigstar \: \color{navy}{ \boxed{ \bf Surface \: Area _{(Sphere)} \: = \: 4\pi {r}^{2} }} \: \color{black}\bigstar$

♣️ Volume Of Sphere :

$\bigstar \: \color{navy}{ \boxed{ \bf Volume _{(Sphere)} \: = \: \frac{4}{3} \pi {r}^{3} }} \: \color{black}\bigstar$

Where,

• $\displaystyle \bf \pi = \frac{22}{7}$

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Solution :-

First, We have to find the radius of sphere :

Given :

• Radius of sphere = 2.1 cm

According to question by using formula we get,

$\implies \: \bf Surface \: Area _{(Sphere)} \: = \: 4\pi {r}^{2}$

$\displaystyle \implies \: \sf Surface \: Area _{(Sphere)} \: = \: 4 \times \frac{22}{7} \times {(2.1)}^{2}$

$\displaystyle \implies \: \sf Surface \: Area _{(Sphere)} \: = \: 4 \times \frac{22}{7} \times \frac{21}{10} \times \frac{21}{10}$

$\displaystyle \implies \: \sf Surface \: Area _{(Sphere)} \: = \: \cancel\frac{1386}{25}$

$\displaystyle \implies \: \sf Surface \: Area _{(Sphere)} \: = \: \frac{55.44 \: {cm}^{2} }{1}$

$\displaystyle \implies \: \bf \red{Surface \: Area _{(Sphere)} \: = \: 55.44 \: {cm}^{2} }$

∴ Hence, The surface area of sphere is 55.44 cm² .

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Now, We have to find the volume of sphere :

Given :

• Radius of sphere = 2.1 cm

According to the question by using formula we get,

$\displaystyle \implies \: \bf Volume _{(Sphere)} \: = \: \frac{4}{3} \pi {r}^{3}$

$\displaystyle \implies \: \sf Volume _{(Sphere)} \: = \: \frac{4}{3} \times \frac{22}{7} \ \times {(2.1)}^{3}$

$\displaystyle \implies \: \sf Volume _{(Sphere)} \: = \: \frac{4}{3} \times \frac{22}{7} \ \times 2.1 \times 2.1 \times 2.1$

$\displaystyle \implies \: \bf \red{Volume _{(Sphere)} \: = \: 38.80 8 \: {cm}^{3} }$

∴ Hence, The volume of sphere is 38.808 cm³ .

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