Find the surface area of a sphere of radius
(i) $ 10.5 \mathrm{~cm} $
(ii) $ 5.6 \mathrm{~cm} $
(iii) $ 14 \mathrm{~cm} $.

To do:

We have to find the surface area of the given spheres.

Solution:

(i) Radius of the sphere $(r) = 10.5\ cm$

Therefore,

Surface area of the sphere $= 4\pi r^2$

$=4 \times \frac{22}{7}(10.5)^{2}$

$=4 \times \frac{22}{7} \times \frac{21}{2} \times \frac{21}{2}$

$=1386 \mathrm{~cm}^{2}$

(ii) Radius of the sphere $(r)=5.6 \mathrm{~cm}$

Therefore,

Surface area of the sphere $=4 \pi r^{2}$

$=4 \times \frac{22}{7} \times(5.6)^{2}$

$=4 \times \frac{22}{7} \times \frac{56}{10} \times \frac{56}{10}$

$=\frac{39424}{100}$

$=394.24 \mathrm{~cm}^{2}$

(iii) Radius of the sphere $(r)=14 \mathrm{~cm}$

Therefore,

Surface area of the sphere $=4 \pi r^{2}$

$=4 \times \frac{22}{7} \times(14)^{2}$

$=4 \times \frac{22}{7} \times 14 \times 14$

$=2464 \mathrm{~cm}^{2}$

Tutorialspoint

Simply Easy Learning

Updated on: 10-Oct-2022

23 Views

Kickstart Your Career

Get certified by completing the course

Get Started