Question

6. Find the radius of a sphere whose surface area is154cm^2​

Answer 1

Given :-

Surface area of sphere =

$154 \: {cm}^{2}$

To find :-

Radius of sphere

Solution :-

As we know ,

Surface area of sphere =

$4\pi {r}^{2}$

As surface area is given so ,

$154 = 4\pi {r}^{2}$

$154 = 4 \times \frac{22}{7} \times {r}^{2}$

${r}^{2} = 154 \times \frac{7}{4 \times 22}$

${r}^{2} = \frac{7 \times 7}{4}$

${r}^{2} = \: \frac{49}{4}$

${r}^{2} = 12.25$

$r = \sqrt{12.25}$

$r = 3.5 \: cm$

So radius of sphere is 3.5cm

Note :-

Pie is taken as

$\frac{22}{7}$

Formula used :-

Surface area of sphere =

$4\pi {r}^{2}$

Hope it helps you