Question:
If the areas of circular bases of a frustum of a cone are 4 cm2 and 9 cm2 respectively and the height of the frustum is 12 cm. What is the volume of the frustum?
Solution:
Area of circular bases of frustum is
$A_{1}=4 \mathrm{~cm}^{2}$
$A_{2}=9 \mathrm{~cm}^{2}$
The height of frustum h = 12 cm
Now, the volume of frustum
$V=\frac{h}{3}\left\{A_{1}+A_{2}+\sqrt{A_{1} A_{2}}\right\}$
$=\frac{12}{3}\{4+9+\sqrt{4 \times 9}\}$
$=4\{13+6\}$
$V=76 \mathrm{~cm}^{3}$
Click here to get exam-ready with eSaral
For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.