Page 48 - Math Course 3 (Book 2)

Geometric Surface Area: Pyramids
Mo. 8

Lesson 2 Key Concept

KEY CONCEPTS: Surface Area of a Regular Pyramid

1. Find lateral areas of pyramids. If a regular pyramid has a surface
2. Find surface areas of pyramids.
area of T square units, a slant
height of units, and its base
has a perimeter of P units
MO. 8 - L2a and an area of B square
1
Lateral and Surface Areas of units, then T = P + B
2
Pyramids

Vocabulary A-Z Lateral Area of a Regular Pyramid
Let us learn some vocabulary If a regular pyramid has a lateral

area of L square units, a slant
regular pyramid height of units, and its base
The base of a pyramid is a regular polygon and the has a perimeter of P units,
1
segment with endpoints that are the center of the then L = P
2
base and the vertex is perpendicular to the base.

altitude
Let’s Begin

slant height base
Find Lateral Area

Regular square pyramid
Example

slant height
All of the lateral faces are congruent isosceles CANDLES
triangles. The height of each lateral face is called A candle store offers a pyramidal
the slant height of the pyramid. candle that burns for 20 hours.
The square base is 6 centimeters
on a side and the slant height of
the candle is 22 centimeters. Find
the lateral area of the candle.

We need to find the lateral area of the square
pyramid. The sides of the base measure 6
centimeters, so the perimeter is 4(6) or 24
slant height centimeters

40