If the surface area of sphere is 616 cm2, then its radius is A) 3.5 c

1.	If the surface area of sphere is 616 cm2, then its radius is A) 3.5 cm B) 7 cm C) 14 cm D) 21 cm
Answer» Correct option is (B) 7 cm Let radius of the sphere is r cm. \(\therefore\) \(4\pi r^2=616\) \((\because\) Surface area of sphere \(=4\pi r^2)\) \(\Rightarrow\) \(r^2=\frac{616}{4\pi}=\frac{616\times7}{4\times22}\) \(=\frac{28\times7}4=7\times7=7^2\) \(\Rightarrow\) r = 7 Hence, radius of sphere is 7 cm. Correct option is B) 7 cm

If the surface area of sphere is 616 cm2, then its radius is A) 3.5 cm B) 7 cm C) 14 cm D) 21 cm

Answer»

Correct option is (B) 7 cm

Let radius of the sphere is r cm.

\(\therefore\) \(4\pi r^2=616\) \((\because\) Surface area of sphere \(=4\pi r^2)\)

\(\Rightarrow\) \(r^2=\frac{616}{4\pi}=\frac{616\times7}{4\times22}\)

\(=\frac{28\times7}4=7\times7=7^2\)

\(\Rightarrow\) r = 7

Hence, radius of sphere is 7 cm.

Correct option is B) 7 cm