Question

A cone has a slant height of 9 cm and a base of radius of 7 cm. Find (i) its curved surface area (ii) total surface area.

Answer 1

Radius of cone (r) = 7 cm
Slant height of cone (l) = 9 cm
(i) Curved surface area of a cone = πrl
$$\begin{gathered} =\frac{22}{7}\times 9\times 7 \\ =198\mathrm{Sq}\mathrm{cm} \end{gathered}$$

(ii) Total surface area of a cone = πr(l + r)
$$\begin{gathered} =\frac{22}{7}\times 7\times \left(9+7\right) \\ =\frac{22}{7}\times 7\times 16 \\ =352\mathrm{Sq}\mathrm{cm} \end{gathered}$$