The radius of a cone is $$5$$cm and vertical height is $$12$$cm. Find the area of the curved surface.
Correct option is A. $$204.28 cm^2$$.
Here,
$$r=5\,cm$$
$$h=12\,cm$$.
We know,
$$l^2=r^2+h^2$$
$$\implies$$ $$l=\sqrt{r^2+h^2}$$
$$\implies$$ $$l=\sqrt{(5)^2+(12)^2}$$
$$\implies$$ $$l=\sqrt{25+144}$$
$$\implies$$ $$l=\sqrt{169}$$
$$\therefore$$ $$l=13\,cm$$.
Therefore, Area of curved surface of cone $$=\pi r l$$
$$=\dfrac{22}{7}\times 5\times 13$$
$$=204.28\,cm^2$$.