Question

The radius of the base of a cone is 5 cm and its height is 12 cm. Its curved surface area is

(a) $60\pi c{m}^2$ (b) $65\pi c{m}^2$ (c) $30\pi c{m}^2$ (d) none of these

Answer 1

Given:radius=5 cm, height=12 cm
therefore slant height(l)=$\sqrt{r^2+h^2}$
=$\sqrt{5^2+{12}^2}$
=$\sqrt{25+144}$
=$\sqrt{169}$=13

curved surface area of cone=π$\times$ r$\times$ l
=π$\times$ 5$\times$ 13=65π $c{m}^2$
(b) 65π $c{m}^2$