Question

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

Answer 1

Given :-

• radius of sphere = 21 cm

To Find :-

• sruface area of a sphere ?

Solution :-

we know that,

$\boxed{ \bold{surface \: area \: of \: sphere = 4\pi {r}^{2} }}$

$\bold{: \implies 4 \times \frac{22}{7} \times {21}^{2} } \: \: \: \: \: \: \: \: \: \\ \\ \bold{ : \implies4 \times \frac{22}{ \cancel{7} } \times \cancel{ 21} \times 21 } \\ \\ \bold{: \implies 4 \times 22 \times 3 \times 21} \: \: \: \: \\ \\ \bold{: \implies \underline{5544} } \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:$

so, surface area of sphere is 5544 cm²

Answer 2

Answer:

Hence, surface area of Sphere will be 5544 Sq. cm

Step-by-step explanation:

In context to question asked,

We have to determine the surface area of the sphere.

As per question,

We have,

Radius of sphere = 21 cm

As we know that,

Sphere is a three dimensional figure.

The surface area of sphere can be determined by using formula,

$Area = 4 \Pi r^2$

So, for determining the surface area we will put the value of r given in the question in above formula,

Thus we will get,

$Area = 4 \Pi r^2\\=> 4 \times \frac{22}{7} \times 21 \times 21\\=>4 \times 22 \times 21\times 3\\=>5544\:cm^2$