Question

If the curved surface area of a hemisphere is 2772 $c{m}^2$, then its diameter is -

• A. 42 cm
• B. 21 cm
• C. 20 cm
• D. 40 cm

Answer 1

Answer: (A)

42 cm

$CSA=2\pi r^2=2772c{m}^2$

$2\times \frac{22}{7}\times r^2=2772$

$r^2=\frac{126\times 7}{2}$

$=63\times 7$

$r^2=3^2\times 7^2$

$r=21cm$

Since $d$=$2r$

$=42cm$