Question

What is the surface area of a cone with the diameter of 12 meters and a slant height of 13.4 meters?

Answer 1

$\begin{gathered} SA=\pi rs+\pi r^2 \\ Common\text{ factor} \\ SA=\pi r(s+r) \\ r=\frac{diameter}{2}=\frac{12m}{2}=6m \\ r=6m \\ s=13.4m \\ Hence \\ SA=\pi r(s+r) \\ SA=\pi(6m)(13.4m+6m) \\ SA=365.68m^2 \\ The\text{ surface area is 365.68m}^2 \end{gathered}$