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.