Question

The radii of the ends of a frustum of a cone $45cm$ high are $28cm$ and and $7cm$. Find its volume, the curved surface area and the total surface area. Take $\pi =22/7$

Answer 1

$\begin{array}{c}fromquestion\\ \frac{x}{7}=45+\frac{x}{28}\\ x=15cm\\ areaoffrustumcone\\ =\frac{1}{3}\times \pi \times {\left(28\right)}^2\times 60\\ =\frac{1}{3}\pi {\left(7\right)}^2\times 15\\ =0.377m^3\\ andsurfacearea=\pi \times 28\times \sqrt{{28}^2+{60}^2}-\pi \times 7\times \sqrt{{15}^2+7^2}\\ =0.5460m^2\end{array}$