Question

Question 1
A drinking glass is in the shape of a 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.

Answer 1

We have R = 2 cm, r = 1 cm and h = 14 cm
Volume of frustum
$=\frac{1}{3}\pi h(R^2+r^2+Rr)$
$=\frac{1}{3}\pi \times 14(2^2+1^2+2)$
$=\frac{1}{3}\times \frac{22}{7}\times 14\times 7$
$=102\frac{2}{3}c{m}^3$