Question

A drinking glass is in the shape of the frustum of a cone of height 14 cm. The diameters of its two circular ends are 4 cm and 2 cm. Find the capacity of the glass.
[Use $\mathrm{\pi }=\frac{22}{7}$]

Answer 1

Capacity of the glass = $\frac{\mathrm{\pi }h}{3}\left(R^2+Rr+r^2\right)$
$$\begin{gathered} =\frac{22\times 14}{7\times 3}\left(2^2+2\times 1+1^2\right)\left[\because R=\frac{4}{2}\mathrm{and}r=\frac{2}{2}\right] \\ =\frac{22\times 14}{7\times 3}\times 7 \\ =\frac{308}{3}{\mathrm{cm}}^3 \end{gathered}$$
Hence, the capacity of the glass is $\frac{308}{3}{\mathrm{cm}}^3$