Question

If a sphere is cut into two hemispheres whose total surface area is
90 cm², then what is the surface area of sphere?​

Answer 1

The surface area of sphere is 60 $cm^{2}$

Step-by-step explanation:

When a sphere is cut into two hemispheres, the total surface area of the  two hemispheres is $2\times(2\pi r^{2} +\pi r^{2} )= 6\pi r^{2}$

Given total surface area is 90 $cm^{2}$.

Therefore, $6\pi r^{2}$ = 90

$\Rightarrow$$\pi r^{2} = \frac{90}{6}$ = 15 $cm^{2}$

surface area of sphere= $4\pi r^{2}$ = $4\times 15 cm^{2}$ = 60 $cm^{2}$

Therefore ,

the surface area of sphere is 60 $cm^{2}$