1. The volume of a three-dimensional figure is the number of cubes it can hold. Each cube represents a unit of measure called a cubic unit.

2. To find a prism’s volume, multiply its length by its width by its height.
4 cm · 3 cm · 1cm = 12 cm3
1 cm
4 cm
3 cm
length · width · height = volume
area of
base
· height = volume

3. The volume of a rectangular prism is the area of its base times its height. This formula can be used to find the volume of any prism.
VOLUME OF A PRISM
The volume V of a prism is the area of its base B times its height h.
V = Bh

4. Example 1
Find the volume of the prism.
4 ft
4 ft
12 ft
V = Bh
Use the formula.
The bases are rectangles.
The area of each rectangular base is 12 · 4 = 48
V = 48 · 4
Substitute for B and h.
V = 192
Multiply.
The volume of the prism is 192 ft3.

5. Example 2
Find the volume of the prism.
V = Bh
Use the formula.
The base is a triangle.
The base is · 3 · 4 = 6
1 2
V = 6 · 6
Substitute for B and h.
V = 36
Multiply.
The volume of the prism is 36 cm3.

6. Find the volume of the prism.
Example 3
Find the volume of the prism.
6 ft
6 ft
8 ft
V = Bh
Use the formula.
The bases are rectangles.
The area of each rectangular base is 8 · 6 = 48
V = 48 · 6
Substitute for B and h.
V = 288
Multiply.
The volume to the nearest tenth is 288 ft3.

7. Find the volume of the prism.
Example 4
Find the volume of the prism.
5 in
4 in.
1.5 in.
V = Bh
Use the formula.
The base is a triangle.
The base is · 1.5 · 5 = 3.75
1 2
V = 3.75 · 4
Substitute for B and h.
V = 15
Multiply.
The volume of the prism is 15 in3.

8. Lesson Quiz: Part I
Find how many cubes the prism holds. Then give the prisms volume. 1. 2.
48 cubic units
792 cm3