(7) Lesson 8.4

1. Find the area of each figure. Round to the nearest tenth if necessary.
1. 2.
3. What is the area of the figure at
the right? Round to the nearest
tenth.
Course 2, Lesson 8-4

2. Course 2, Lesson 8-4
ANSWERS
1. 45 cm²
2. 67 mi²
3. 85.7 in²

3. Geometry
Course 2, Lesson 8-4
HOW do measurements help you
describe real-world objects?

4. Course 2, Lesson 8-4 Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and
Council of Chief State School Officers. All rights reserved.
Geometry
• 7.G.6
Solve real-world and mathematical problems involving area, volume
and surface area of two- and three-dimensional objects composed of
triangles, quadrilaterals, polygons, cubes, and right prisms.
Mathematical Practices
1 Make sense of problems and persevere in solving them.
2 Reason abstractly and quantitatively.
3 Construct viable arguments and critique the reasoning of others.
4 Model with mathematics.

5. • To find the volume of rectangular prism
• To find the volume of a triangular prism
Course 2, Lesson 8-4
Geometry

6. Course 2, Lesson 8-4
Geometry
• volume

7. Course 2, Lesson 8-4
Geometry
Words The volume V of a
rectangular prism is the
product of the length , the
width w, and the height h. It
is also the area of the base B
times the height h.
Symbols V = wh or V = Bh
Model

8. 1
Need Another Example?
2
3
4
Step-by-Step Example
1. Find the volume of the rectangular prism.
V = ℓwh
The volume is 60 cubic centimeters or 60 cm3.
Volume of a prism
V = 5 • 4 • 3 ℓ = 5, w = 4, and h = 3
V = 60 Multiply.

9. Answer
Need Another Example?
Find the volume of the rectangular prism.
24 cm3

10. Course 2, Lesson 8-4
Geometry
Words The volume V of a triangular Model
prism is the area of the base
B times the height h.
Symbols V = Bh, where B is the area
of the base.

11. 1
Need Another Example?
2
3
4
5
6
Step-by-Step Example
2. Find the volume of the
triangular prism shown.
V = Bh
The volume is 216 cubic feet or 216 ft3.
Volume of a prism
V = • 6 • 8 h
V = • 6 • 8 9 The height of the prism is 9.
The area of the triangle is • 6 • 8, so
replace B with • 6 • 8.
V = 216 Multiply.
Replace B with • 6 • 8.

12. Answer
Need Another Example?
Find the volume of the triangular prism.
315 m3

13. 1
Need Another Example?
2
3
Step-by-Step Example
3. Which lunch box holds more food?
V = ℓwh
Since 285 in3 > 281.25 in3, Lunch Box B holds more food.
V = 7.5 • 3.75 • 10
Find the volume of each lunch box. Then compare.
V = 281.25 in3
Lunch Box A Lunch Box B
V = ℓwh
V = 8 • 3.75 • 9.5
V = 285 in3

14. Answer
Need Another Example?
The game Planet Bugs comes in the box shown below.
The game Fire and Ice comes in a box that measures
9 inches by 5 inches by 4 inches. Which game box has
the greater volume?
Planet Bugs

15. How did what you learned
today help you answer the
Course 2, Lesson 8-4
Geometry
HOW do measurements help you
describe real-world objects?

16. How did what you learned
today help you answer the
Course 2, Lesson 8-4
Geometry
HOW do measurements help you
describe real-world objects?
Sample answers:
• To find the amount a rectangular-shaped box can hold
• To find the amount a triangular-shaped box can hold

17. Measure and find the
volume of a rectangular
or triangular prism found
in your classroom.
Course 2, Lesson 8-4
Ratios and Proportional RelationshipsFunctionsGeometry