### Theory:

Hemisphere:
A one half of a sphere is called a hemisphere.
Curved surface area:
$$C. S. A.$$ $$=$$ $$\frac{\text{Surface area of a sphere}}{2}$$

$$=$$ $\frac{4\mathrm{\pi }{r}^{2}}{2}$

$$=$$ $2\mathrm{\pi }{r}^{2}$

Curved surface area of a hemisphere $$=$$ $2\mathrm{\pi }{r}^{2}$ sq. units.
Total surface area:
$$T. S. A.$$ $$=$$ Curved surface area of a hemisphere $$+$$ Area of the top region

$$=$$ $2\mathrm{\pi }{r}^{2}$ $$+$$ $$\pi r^2$$

$$=$$ $$3 \pi r^2$$

Total surface area of a hemisphere $$=$$ $$3 \pi r^2$$ sq. units.

Important!
Properties of hemisphere is same as the properties of sphere.