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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
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
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
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
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
Objective #1: Use scale drawings Divide each side by 4. Simplify. Answer: The scale is 1 inch = 3 feet. Example 3-2b
Objective #1: Use scale drawings Example 3-1c
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
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
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
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
Objective #2: Construct scale drawings Divide each side by 4. Simplify. On the drawing, the width is 1.75 or inches. Example 3-3c
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
Objective #2: Construct scale drawings Answer: Example 3-3e
Objective #2: Construct scale drawings Example 3-3f
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
Objective #2: Construct scale drawings Answer: Example 3-3g
End of Lesson 3