1. Splash Screen

2. Objective #1: Use scale drawings Example 1 Find Actual Measurements
Example 2 Determine the Scale
Objective #2: Construct scale drawings
Example 3 Construct a Scale Drawing
Lesson 3 Contents

3. Objective #1: Use scale drawings 9-19 odd, (alt. 9, 13, 17)
Practice and Apply
Objective #1: Use scale drawings
9-19 odd, (alt. 9, 13, 17)
Objective #2: Construct scale drawings 21
Maintaining Your Skills
26-36
Lesson 3 Contents

5. Objective #1: Use scale drawings
Map A map has a scale of 1 inch = 8 miles. Two towns are 3.25 inches apart on the map. What is the actual distance between the two towns?
Let x represent the actual distance between the two towns. Write and solve a proportion.
map distance
actual distance
Find the cross products.
Simplify.
Answer: The actual distance between the two towns is 26 miles.
Example 3-1a

6. Objective #1: Use scale drawings
Map A map has a scale of 1 inch = 8 miles. Two towns are 3.25 inches apart on the map. What is the scale factor?
To find the scale factor, write the ratio of 1 inch to 8 miles in simplest form.
Convert 8 miles to inches.
Answer: The scale factor is . That is, each measurement on the map is the actual measurement.
Example 3-1b

7. Objective #1: Use scale drawings
Model Car A model car is 4 inches long. The actual car is 12 feet long. What is the scale of the model?
Write the ratio of the length of the model to the actual length of the car. Then solve a proportion in which the length of the model is 1 inch and the actual length is x feet.
model length
actual length
Find the cross products.
Simplify.
Example 3-2a

8. Objective #1: Use scale drawings
Divide each side by 4.
Simplify.
Answer: The scale is 1 inch = 3 feet.
Example 3-2b

9. Objective #1: Use scale drawings
Example 3-1c

10. Objective #1: Use scale drawings
Scale Drawing A scale drawing of a new house has a scale of 1 inch = 4 feet. The height of the living room ceiling is 2.75 inches on the scale drawing.
a. What is the actual height of the ceiling?
b. What is the scale factor?
Answer: 11 feet
Answer:
Example 3-1c

11. Objective #1: Use scale drawings
Log Cabin A model log cabin is 12 inches high. The actual log cabin is 42 feet high. What is the scale of the model?
Answer: The scale is 1 inch = 3.5 feet.
Example 3-2c

12. Objective #2: Construct scale drawings
Patio Design Sheila is designing a patio that is 16 feet long and 14 feet wide. Make a scale drawing of the patio. Use a scale of 0.5 inch = 4 feet.
Step 1 Find the measure of the patio’s length on the drawing. Let x represent the length.
drawing length
actual length
Find the cross products.
Simplify.
Example 3-3a

13. Objective #2: Construct scale drawings
Divide each side by 4.
On the drawing, the length is 2 inches.
Step 2 Find the measure of the patio’s width on the drawing. Let w represent the width.
drawing width
actual width
Find the cross products.
Simplify.
Example 3-3b

14. Objective #2: Construct scale drawings
Divide each side by 4.
Simplify.
On the drawing, the width is 1.75 or inches.
Example 3-3c

15. Objective #2: Construct scale drawings
Step 3 Make the scale drawing. Use -inch grid paper. Since 2 inches = 8 squares and inches = 7 squares, draw a rectangle that is 8 squares by 7 squares.
Example 3-3d

16. Objective #2: Construct scale drawings
Answer:
Example 3-3e

17. Objective #2: Construct scale drawings
Example 3-3f

18. Objective #2: Construct scale drawings
Gardening Bob is designing a garden that is 18 feet long and 14 feet wide. Make a scale drawing of the garden. Use a scale of 0.5 inch = 4 feet.
Answer: The length is inches = 9 squares and the width is inches = 7 squares.
Example 3-3f

19. Objective #2: Construct scale drawings
Answer:
Example 3-3g

21. End of Lesson 3