1. Scale Drawings and Scale Models
5-9
Scale Drawings and Scale Models
Course 2
Warm Up
Problem of the Day
Lesson Presentation

2. Scale Drawings and Scale Models
Course 2
5-9
Scale Drawings and Scale Models
Warm Up
Write each fraction in the simplest form. 4 48 1 12 9
135 1 15 2. 1.
Convert the following measurements.
inches = feet 16
feet = inches
222
inches = feet 27

3. Scale Drawings and Scale Models
Course 2
5-9
Scale Drawings and Scale Models
Problem of the Day
A toy model of a 200 foot dinosaur is 3 in. long. How many times as long as the model is the dinosaur?
800

4. Scale Drawings and Scale Models
Course 2
5-9
Scale Drawings and Scale Models
Learn to understand ratios and proportions in scale drawings. Learn to use ratios and proportions with scale.

5. Insert Lesson Title Here
Course 2
5-9
Scale Drawings and Scale Models
Insert Lesson Title Here
Vocabulary
scale model
scale factor
scale
scale drawing

6. Scale Models and Scale Drawings
Course 2
5-9
Scale Models and Scale Drawings
This HO gauge model train is a scale model of a historic train. A scale model is a proportional model of a three-dimensional object. Its dimensions are related to the dimensions of the actual object by a ratio called the scale factor. The scale factor of an HO
gauge model train is 1 87
This means that each dimension of the model is of the corresponding dimension of the actual train. 1 87

7. Scale Models and Scale Drawings
Course 2
5-9
Scale Models and Scale Drawings
A scale is the ratio between two sets of measurements. Scales can use the same units or different units. The photograph shows a scale drawing of the model train.
A scale drawing is a proportional drawing of an object. Both scale drawings and scale models can be smaller or larger than the objects they represent.

8. Additional Example 1: Finding a Scale Factor
Course 2
5-9
Scale Drawings and Scale Models
Additional Example 1: Finding a Scale Factor
Identify the scale factor.
Room
Blueprint
Length (in.)
144 18
Width (in.)
108
13.5
blueprint length
room length 18
144
Write a ratio using one of the
dimensions. = 1 8 =
Simplify.
A scale factor is always the ratio of the model’s dimensions to the actual object’s dimensions.
Caution! 1 8
The scale factor is .

9. Insert Lesson Title Here
Course 2
5-9
Scale Drawings and Scale Models
Insert Lesson Title Here
Check It Out: Example 1
Identify the scale factor.
Model Aircraft
Blueprint
Length (in.) 12 2
Wing span (in.) 18 3
blueprint length
aircraft length 2 12 =
Write a ratio using one of the dimensions. 1 6 =
Simplify.
The scale factor is . This is reasonable because of the length of the model is 3 in. The length of the blueprint is 2, which is less. is less than . 1 6 4

10. Additional Example 2: Using Scale Factors to Find Unknown Lengths
Course 2
5-9
Scale Drawings and Scale Models
Additional Example 2: Using Scale Factors to Find Unknown Lengths
A photograph was enlarged and made into a poster. The poster is 20.5 inches by 36 inches.
The scale factor is . Find the size of the photograph. 5 1
poster
photo 5 1
Think: = 36 l 5 1 =
Write a proportion to find the length l.
5l = 36
Find the cross products.
l = 7.2
Divide.

11. Additional Example 2 Continued
Course 2
5-9
Scale Drawings and Scale Models
Additional Example 2 Continued
A photograph was enlarged and made into a poster. The poster is 20.5 inches by 36 inches.
The scale factor is . Find the size of the photograph. 5 1
poster
photo 5 1
Think: =
20.5 w 5 1
Write a proportion to find the width w. =
5w = 20.5
Find the cross products.
w = 4.1
Divide.
The photo is 7.2 in. long and 4.1 in. wide.

12. Scale Drawings and Scale Models
Course 2
5-9
Scale Drawings and Scale Models
Check It Out: Example 2
Mary’s father made her a dollhouse which was modeled after the blueprint of their home. The blueprint is 24 inches by 45 inches. The scale
factor is Find the size of the dollhouse.
1.5 1
dollhouse
blueprint
1.5 1
Think: = l 45 =
1.5 1
Write a proportion to find the length l.
Find the cross products.
l = 45 · 1.5
l = 67.5
Multiply.

13. Check It Out: 2 Continued
Course 2
5-9
Scale Drawings and Scale Models
Check It Out: 2 Continued
Mary’s father made her a dollhouse which was modeled after the blueprint of their home. The blueprint is 24 inches by 45 inches. The scale
factor is Find the size of the dollhouse.
1.5 1
dollhouse
blueprint
1.5 1
Think: = w 24
1.5 1
Write a proportion to find the width w. =
w = 24 · 1.5
Find the cross products.
w = 36
Multiply.
The dollhouse is 67.5 inches long and 36 inches wide.

14. Additional Example 3: Measurement Application
Course 2
5-9
Scale Drawings and Scale Models
Additional Example 3: Measurement Application
On a road map, the distance between Pittsburgh and Philadelphia is 7.5 inches. What is the actual distance between the cities if the map scale is 1.5 inches = 60 miles?
Let d be the actual distance between the cities.
1.5 60
7.5 d =
Write a proportion.
1.5 · d = 60 · 7.5
Find the cross products.
1.5d = 450
Multiply.
1.5d
1.5
450
1.5 =
Divide both sides by 1.5.
d = 300
The distance between the cities is 300 miles.

15. Insert Lesson Title Here
Course 2
5-9
Scale Drawings and Scale Models
Insert Lesson Title Here
Check It Out: Example 3
On a road map, the distance between Dallas and Houston is 7 inches. What is the actual distance between the cities if the map scale is 1 inch = 50 kilometers?
Let d be the actual distance between the cities. 1 50 7 d =
Write a proportion.
1 · d = 50 · 7
Find the cross products.
1d = 350
Multiply.
d = 350
The distance between the cities is 350 kilometers.

16. Scale Drawings and Scale Models Insert Lesson Title Here
Course 2
5-9
Scale Drawings and Scale Models
Insert Lesson Title Here
Lesson Quiz: Part I
Identify the scale factor. 1.
Statue of Liberty
Model
Height (in.)
1,824 8 1
228 2.
On a scale drawing, a kitchen wall is 6 inches long.
The scale factor is What is the length of the
actual wall? 1 24
144 inches, or 12 feet

17. Scale Drawings and Scale Models Insert Lesson Title Here
Course 2
5-9
Scale Drawings and Scale Models
Insert Lesson Title Here
Lesson Quiz: Part II 3.
On a road map, the distance from Green Bay to
Chicago is 11 cm. What is the actual distance
between the cities if the map scale is 3 cm = 90 km?
330 km