“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...
(8) Lesson 8.1
1. Course 3, Lesson 8-1 .
1. Mr. Jefferies wants to double the dimensions of his driveway.
The driveway has a length of 15 feet and a width of 12 feet.
What will be the perimeter of his new driveway?
For each pair of similar figures, determine the perimeter of the
second figure.
2. 3.
4. Jared has a 4-inch wide by 5-inch high photo. He wants to
enlarge the photo with a scale of 1:2. What is the area of the
enlarged photo?
2. Course 3, Lesson 8-1 .
ANSWERS
1. 108 feet
2. 27 ft
3. 10 cm
4. 80 sq. in.
3. WHY are formulas important
in math and science?
Geometry
Course 3, Lesson 8-1 .
7. Course 3, Lesson 8-1
Geometry
Words The volume V of a cylinder with radius r is the area of the base
B times the height h.
Model
Symbols V = Bh, where B = πr2 or V = πr2h
8. 1
Need Another Example?
2
3
4
Step-by-Step Example
1. Find the volume of the cylinder. Round to the
nearest tenth.
V = πr2h Volume of a cylinder
V = π(5)2(8.3) Replace r with 5 and h with 8.3.
Use a calculator.
The volume is about 651.9 cubic centimeters.
10. 1
Need Another Example?
2
3
4
Step-by-Step Example
2. Find the volume of a cylinder with a diameter of 16 inches
and a height of 20 inches. Round to the nearest tenth.
V = πr2h Volume of a cylinder
V = π(8)2(20) The diameter is 16 so the radius is 8. Replace h with 20.
The volume is about 4,021.2 cubic inches.
Use a calculator.V ≈ 4,021.2
11. Answer
Need Another Example?
Find the volume of a cylinder with a diameter of
12 meters and a height of 4 meters. Round to
the nearest tenth.
452.4 m3
12. 1
Need Another Example?
2
3
4
5
Step-by-Step Example
3. A metal paperweight is in the shape of a cylinder. The paperweight
has a height of 1.5 inches and a diameter of 2 inches. How much
does the paperweight weigh if 1 cubic inch weighs 1.8 ounces?
Round to the nearest tenth.
V = πr2h Volume of a cylinder
V = π(1)21.5 Replace r with 1 and h with 1.5.
First find the volume of the paperweight.
V ≈ 4.7
To find the weight of the paperweight, multiply the volume by 1.8.
4.7(1.8) = 8.46
Simplify
So, the weight of the paperweight is about 8.5 ounces.
13. Answer
Need Another Example?
A cylindrical container of ice cream is 10 centimeters
in diameter and 12 centimeters tall. How long will it
take for all of the ice cream in the container to melt if
it melts at a rate of 2.1 cubic centimeters every
minute? Round to the nearest tenth.
448.8 min or 7.5 h
14. 1
Need Another Example?
2
3
Step-by-Step Example
4. Tanya uses cube-shaped
beads to make jewelry.
Each bead has a circular
hole through the middle.
Find the volume of each
bead.
Rectangular Prism
The bead is made of one rectangular prism and one cylinder. Find the
volume of each solid. Then subtract to find the volume of the bead.
The volume of the bead is 1,728 – 37.7 or 1,690.3 cubic millimeters.
Cylinder
V = Bh
V = (12 • 12)12 or 1,728
V = Bh
V = (π • 12)12 or 37.7
15. Answer
Need Another Example?
A roll of paper towels has the dimensions
shown. Find the volume of the roll. Round
to the nearest tenth.
3,271.2 cm3
16. How did what you learned
today help you answer the
WHY are formulas important
in math and science?
Course 3, Lesson 8-1
Geometry
17. How did what you learned
today help you answer the
WHY are formulas important
in math and science?
Course 3, Lesson 8-1
Sample answers:
• The formula is used to find the volume of a
cylinder.
• In a composite figure, several formulas are used to find
the volume of more than one type of figure.
2V r h
Geometry
18. A cylindrical bale of hay
has a height of 5 feet
and a diameter of 5 feet.
What is its approximate
volume to the nearest
cubic foot?
Course 3, Lesson 8-1
Ratios and Proportional RelationshipsFunctionsGeometry
