Question

Find the difference between total surface area & curved surface area of a hemisphere of radius $21cm$.

• A. $1376c{m}^2$
• B. $1386c{m}^2$
• C. $1396c{m}^2$
• D. $1404c{m}^2$

Answer 1

The correct option is B $1386c{m}^2$

Curved Surface Area of a hemisphere of radius 'r' $=2\pi r^2$

Total Surface Area of a hemisphere of radius 'r' $=3\pi r^2$

Hence, required difference $=3\pi r^2-2\pi r^2=\pi r^2=\frac{22}{7}\times 21\times 21=1386{cm}^2$