1. Warm-Up
1. Two similar figures have a scale factor of 2 : 5. If the larger figure has a perimeter of 40 ft, what is the perimeter of the smaller figure?
2. Find x LJK SQR. Find x. J x 14 M 11 12 Q L K 5 x T 8 20 S R

2. Scale Drawings Target: I can interpret scale models.
I can use scale factor to solve problems.

3. Video
Scale Models

4. Group Atlas Activity As a group:
Pick a map in the atlas (must be a map with a scale).
Get familiar with the scale. How many kilometers or miles are represented by 1 inch?
Decide on a trip you would like to take within your chosen map. What city would you like to start at? What city do you want to end at?
Using your scale, figure out how many miles (or kilometers) the actual distance would be.
Convert your answer to whatever measurement you didn’t find.

5. Example 1a
Alan’s map has a scale of 0.4 inches : 40 miles. The distance on the map from Mt. Hood Meadows to Alan’s home is 0.85 inches. What is the actual distance?

6. Example 1b
Mrs. Drake’s map has a scale of 2 inches : 45 miles. The actual distance from Drake’s home to her husband’s home town (Heppner, OR) is 210 miles. Find the distance on the map.

7. Scale Factors of scale models
Many times, scale factors of models are given as a unit-less ratio. If this is the case, you must make sure all of the units in the problem are the same in order to solve.

8. Example 2
A model car is made with a scale factor of 1 inch: 11 inches or
1 : 11. The actual car is 7 feet 4 inches long. How long is the model
car?
Convert 7 feet 4 inches to inches to ft 4 in = 7·12 + 4
match the scale factor: =
= 88 in
Write a proportion using the scale factor 1 : 11.
Use cross products to solve x = 88
x = 8
The model car is 8 inches long.

9. Trains!
Mrs. Drake’s dad used to be the Vice President of the Portland and Western Railroad. He used to drive a lot of trains like the one below. For his birthday, she’d like to make a scale model of this engine. If the scale she wants to use is 1:52 and the actual engine is 65 feet long, how many inches long will her model need to be?

10. Communication Prompt
When have you or a member of your family used a scale drawing? What information did it help you figure out?

11. Exit Problems Homework: Pg. 514-516 #1-3, 5-9, 16, 17, 19, and 21
A map has a scale of 2 inches : 5 miles.
Use the given distance on a map to find the actual distance.
8 in
1 ft 2 in
A model car has a scale of 1 : 24.
The model car is 4 inches long. How long is the actual car in inches? How long in feet?