1. 5.8 Scale Drawing and Models

2. Scale Drawing/Model
Is used to represent an object that is too large or to small to be drawn or built to its actual size and is proportional to the actual.

3. Ratio of the model to the actual
Scale
Ratio of the model to the actual

4. To Find Scale

5. Example 1
The length of a model of a bridge is 16 inches. The actual length of the bridge is 50 yards. What is the scale of the model?
The scale is 1 in = yards

6. Meaning the actual is 24 times as big
Scale Factor
When the scale drawing and model have the same unit of measure.
Example:
Scale: 1 inch = 2 feet
Scale Factor: 1in : 24 in
Meaning the actual is 24 times as big

7. The actual is 96 times the map length
Example 2: A map of a natural history museum shows that the dinosaur exhibit room is 7.25 inches wide. If the scale on the map is 1 inch = 8 feet, what is the width of the actual exhibit room?
Method 1: Using Scale and Proportions
Method 2: Using Scale Factor and Equations
1in = 8 feet
The actual is 96 times the map length
Let a= actual, m= map
a=96m
a=96(7.25)
a=696 inches
58 feet

8. Example 3 Construct a Scale Drawing on Paper
An architect is designing a school courtyard that is 45 feet long and 30 feet wide. Make a scale drawing of the courtyard. Use a scale of 0.5 inch= 10 feet. Use ¼ inch graph paper.
0.5 inches = 2 boxes on the ¼ inch graph paper
Length: 45/10= 4.5 of 2 boxes= 4.5 (2) = 9 boxes
Width: 30/10=3 of 2 boxes= 3(2)= 6 boxes
Draw it

9. Homework
Page 227 (2-16) even