Question

What is the total surface area of hollow hemisphere?

Answer 1

This hemisphere is hollow. It has a total surface area of:
outer surface area + inner surface area + area of ring.
2π(1.25)2 + 2π(1.86/2)2 + ( π(1.25)2 - π(1.86/2)2 )

Answer 2

The total surface area of hollow hemisphere $=2\pi (R^{2} +r^{2} )+\pi (R^{2} -r^{2} )$.

Step-by-step explanation:

Let the inner radius of a hollow hemisphere = r  and

the outer radius of a hollow hemisphere = R

To find, the total surface area of hollow hemisphere = ?

We know thar,

Total surface area = Outer surface area + Inner surface area + Area of ring

$=2\pi R^{2} +2\pi r^{2} +\pi(R^{2}-r^{2}  )$

$=2\pi (R^{2} +r^{2} )+\pi (R^{2} -r^{2} )$

∴ The total surface area of hollow hemisphere $=2\pi (R^{2} +r^{2} )+\pi (R^{2} -r^{2} )$

Hence, the total surface area of hollow hemisphere $=2\pi (R^{2} +r^{2} )+\pi (R^{2} -r^{2} )$.