Question

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

Answer 1

Answer:

Step-by-step explanation:

Given :-

Surface area of sphere = 154 m²

To Find :-

Radius of a sphere

Formula to be used :-

Surface area of sphere = 4πr²

Solution :-

Let 'r' be the radius of sphere

Surface area of sphere = 4πr²

⇒ 154 = 4πr²  

⇒ 154 = 4 x 22/7 x r²

⇒ r²  = 154 x 7/4 x 22 = 49/4

⇒ r = 7/2 cm  

⇒ r = 3.5 cm

Hence, the Radius of a sphere is 3.5 cm.

Answer 2

Answer:-

Radius = 3.5 cm

Explanation:-

Given:-

Area of sphere = 154 cm²

To Find:-

Radius of the sphere

Solution:-

$\boxed{\bold{Surface \: Area \: of \: sphere = 4\pi r^2}}$

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

${\rightarrow} \: 4\times \dfrac{22}{7} r^2 = 154$

${\rightarrow} \: r^2 = 154 \times \dfrac{7}{22 \times 4}$

${\rightarrow} \: r^2 = 7 \times \dfrac{7}{4}$

${\rightarrow} \: r = \sqrt{\dfrac{49}{4}}$

${\rightarrow} \: r = 3.5cm$

$\blue{\boxed{\bold{\pink{Radius\: of \: sphere = 3.5cm}}}}$