Question

Find the radius of a sphere whose surface area is 154 cm2

Answer 1

Let the radius of the sphere be r.
Surface area of sphere = 154
So, $4\pi r^2 = 154\ cm^2$
r2 = $\frac{154}{4\pi}$

r2 = $\left(\frac{154}{4}\right) \left(\frac{7}{22}\right)$

r2 = $\frac{\text{(154 × 7) }}{\text{ (4 × 22)}}$

r2 = $(\frac{49}{4})$

r = ($\frac{7}{2}$) = 3.5 cm
Therefore, the radius of the sphere whose surface area is 154 cm2 is 3.5 cm.