Question

Total surface area of a hemisphere with radius ${}^{\prime }{r}^{\prime }$ units, will be equal to

• A. $4\pi r^2$
• B. $3\pi r^2$
• C. $\frac{4}{3}\pi r^3$
• D. $\frac{2}{3}\pi r^3$

Answer 1

The correct option is B $3\pi r^2$

Given Solid: Hemisphere
Radius: $r$


Total surface area of a sphere, $S_{sphere}=4\pi r^2$

Total surface area of the hemisphere $=\frac{1}{2}\times S_{sphere}+\text{Area of the circle}=\frac{1}{2}\times 4\pi r^2+\pi r^2=2\pi r^2+\pi r^2=3\pi r^2$