Question

Find the curved surface area and total surface area of a hemisphere of radius 21cm.

• A. CSA = $2772c{m}^2$, TSA = $4158c{m}^2$
• B. CSA = $2772c{m}^2$, TSA = $4676c{m}^2$
• C. CSA = $2079c{m}^2$, TSA = $74564c{m}^2$
• D. CSA = $2126c{m}^2$, TSA =$4253c{m}^2$

Answer 1

The correct option is A CSA = $2772c{m}^2$, TSA = $4158c{m}^2$


Curved surface area = $2\pi r^2$
$=2\times \frac{22}{7}\times 21\times 21$
$=2772c{m}^2$

Total surface area of given hemisphere = $3\pi r^2$
$=3\times \frac{22}{7}\times 21\times 21$
$=4158c{m}^2$
Hence, the correct answer is option (a)