Question

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

Answer 1

Hello!

$\sf Surface\:area = 154\:cm^{2} \\ \\ \implies \sf 4πr^{2} = 154 \\ \\ \implies 4 \times \dfrac{22}{7} \times \sf r^{2} = 154 \\ \\ \implies \sf r^{2} = \dfrac{154\times7}{4\times22} \\ \\ \implies \sf r^{2} = \dfrac{49}{4} \\ \\ \implies \sf r = \dfrac{7}{2} \implies \boxed{\red{\bf{r=3.5\:cm}}}$

Cheers!

Answer 2

Answer:

3.5 cm

Step-by-step explanation:

In the question, the surface area is $154\ cm^{2}$.

we have to find the radius of sphere.

Let r be the radius of the sphere.

we know that,

$Surface\ area = 4\pi\ r^{2}$

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

$\frac{154\times7}{22\times4} = r^{2}$

$r^{2} = 12.25$

$r = \sqrt{12.25}$

r = 3.5

Hence the radius of the sphere is 3.5 cm.