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The volume of a right circular cone is 1232 cm3 and its vertical height is 24 cm. Its curved surface area is
Answer & Solution
Correct Answer:
Option
B
$$\eqalign{
& {\text{Volume of a cone}} = \frac{1}{3}\pi {r^2}h \cr
& \frac{1}{3}\pi {r^2}\left( {24} \right) = 1232{\text{ c}}{{\text{m}}^2} \cr
& {r^2} = \frac{{1232 \times 3 \times 7}}{{24 \times 22}} \cr
& {r^2} = 7 \times 7 \cr
& r = \sqrt {7 \times 7} \cr
& r = 7{\text{ cm}} \cr
& l = \sqrt {{r^2} + {h^2}} \cr
& = \sqrt {{7^2} + {{24}^2}} \cr
& = \sqrt {625} \cr
& = 25 \cr
& {\text{Curved surface area}} = \pi rl \cr
& = \frac{{22}}{7} \times 7 \times 25 \cr
& = 550{\text{ c}}{{\text{m}}^2} \cr} $$
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