The frustum is a pyramid that is the result of chopping off the top of a regular pyramid. That is the reason why it is called a truncated pyramid.

The distance between the base and the top of the pyramid is the height and is denoted by h. Similarly, it has a slant height that is denoted by “s” and two bases (top and bottom), whose area is defined by

and .

We need to find the lateral surface area and the volume of Frustum of regular pyramid formula.

$$V=\frac{h(B_1+B_2+\sqrt{B_1{B}_2})}{3}$$

$$S=\frac{s(P_1+P_2)}{2}$$

Here,
S = Lateral Surface Area

= Perimeter of Bases
h=Height
= Area of bases
s = Slant height
V=Volume

Solved Examples

Question: Find the volume of a frustum of a regular pyramid whose area of bases are 9 cm², 10 cm² respectively and height is 9 cm.

Solution:
Given
B₁ = 9 cm²
B₂ = 10 cm²
h = 9 cm

Volume formula,

V =