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

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

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

map distance

actual distance

Find the cross products.

Simplify.

Answer: The actual distance between the two towns is 26 miles.

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.

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 actuallength of the car. Then solve a proportion in which thelength of the model is 1 inch and the actual length is x feet.

model length

actual length

model length

actual length

Find the cross products.

Simplify.

Objective #1: Use scale drawings

Divide each side by 4.

Simplify.

Answer: The scale is 1 inch = 3 feet.

Objective #1: Use scale drawings

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:

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.

Objective #1: Use 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

drawing length

actual length

Find the cross products.

Simplify.

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

drawing width

actual width

Find the cross products.

Simplify.

Objective #2: Construct scale drawings

Divide each side by 4.

Simplify.

On the drawing, the width is 1.75 or inches.

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.

Objective #2: Construct scale drawings

Answer:

Objective #2: Construct scale drawings

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.

Objective #2: Construct scale drawings

Answer:

Objective #2: Construct scale drawings