The radius of a right circular cone is 3 cm and its height is 4 cm
The radius of a right circular cone is 3 cm and its height is 4 cm. The curved surface of the cone will be
A$$12 \pi \text{ sq.cm}$$
B$$15 \pi \text{ sq.cm
} $$
C$$18 \pi \text{ sq.cm }$$
D$$ 21 \pi \text{ sq.cm} $$
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Answer is \(15 \pi \text{ sq.cm }\)
Explanation:
Slant height of the cone \(l = \sqrt{r^2+h^2}\)
= \(\sqrt{3^2+4^2}\)
= \(\sqrt{9+16}\)
=\(\sqrt{25}=5 \text { cm}\)
\(\therefore\) Area of the curved surface
= \(\pi rl \)
\(=\pi \times3\times5\)
\(= 15 \pi \text{ sq.cm}\)
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