1. Unit 6: Scale Factor and Measurement
How will you measure up?

2. What am I Learning Today?
Indirect Measurement
How will I show that I learned it?
Demonstrate the relationship between similar plane figures using ratio and proportion
Use proportions and similar figures to find unknown measures
Solve real world problems using indirect measurement

3. Conversions
You will need to know that 1 ft = 12 in
Use a proportion to convert 40 inches into feet.
40 = 12x
X = 3.33 ft

4. Conversions
Conversion factor- A numerical factor used to multiply or divide a quantity when converting from one system of units to another.
Ex. 1 feet = 12 inches
Ex feet = 1 mile
Ex. 1 cup = 8 ounces

5. Do you know how tall the Eiffel Tower is
Do you know how tall the Eiffel Tower is? Is there a way to find out without actually measuring it?
What I do know is that on a sunny day, its shadow is 328 feet long.
What could we do to
solve this problem? What
ideas do you have for
determining its height?

6. What is indirect measurement?
Questions Notes
Questions Answers
A technique that uses proportions to find a measurement when it is not possible to measure something directly.
What is indirect measurement?
How can I find the length or height without using standard measuring tools?
Use similar figures and proportions:
1) Draw a sketch to identify similarities
2) Create a proportion substituting values for the
given measurements
3) Solve for X

7. Use the similar triangles to find the height of the tree.6 h __ 3 9 __
Write a proportion using corresponding sides. =
h • 3 = 6 • 9
The cross products are equal.
3h = 54
h is multiplied by 3.
6 ft h
Divide both sides by 3 to undo multiplication. 3h 3
___ 54 3
___ =
3 ft ft.
h = 18
The tree is 18 feet tall.

8. Measurement Application
A rocket casts a shadow that is 91.5 feet long. A 4-foot model rocket casts a shadow that is 3 feet long. How tall is the rocket?
Write a proportion using corresponding sides. h 4 __
91.5 3
____ =
4 • 91.5 = h • 3
The cross products are equal.
366 = 3h
h is multiplied by 3.
366 3
___ 3h 3
___
Divide both sides by 3 to undo multiplication. =
122 = h
The rocket is 122 feet tall.

9. 1. Use the similar triangles to find the height of the post.
2. On a sunny afternoon, a goalpost casts a 75 ft shadow. A 6.5 ft football player next to the goal post has a shadow 19.5 ft long. How tall is the goalpost?
3. A stop sign casts a shadow 8 meters long, while a bush nearby casts a shadow 4.5 meters long. If the stop sign is 3.2 meters high, how tall is the bush? x
15 ft
8 ft
6 ft
20 feet
25 feet
1.8 meters

10. Measuring the Oddities of America
Measure your height to the nearest inch
Let’s make your shadow 12 inches longer than your height
Using this information, determine the heights or shadow lengths of the following large immeasurable objects
Create proportions and solve for the missing piece of information

11. The Jolly Green Giant This monument found in Blue Earth, Minnesota
stands a proud 55 feet
tall.
Using your height and shadow length, find the length of the Jolly Green Giant’s shadow?

12. The World’s Tallest Man
Robert Pershing Wadlow was (and still is) the tallest human being ever recorded.
He reached 8' 11" (272 cm) in height and 490 pounds ( kg) in weight before his death at the age of 22.
What would have been the length of his shadow compared to yours?

13. World’s Tallest Snow Woman
Built in Bethel, Maine,
Olympia Snow Woman
took 28 days and 13
million pounds of snow to
construct. She has a
shadow of 61 feet long.
How tall is this snow woman?

14. The World’s Tallest Arcade Game
This arcade machine
stands 13 feet tall,
has a 70 inch screen,
and plays vintage
video games. It casts
a shadow of 6.5 feet.
If Ms. Attilio is 5 feet tall, how long would her shadow be in comparison?

15. Exit Ticket
Draw a sketch to represent each problem. Set up the proportion and solve. Be sure to label your answer. A flagpole casts a shadow that is 9 feet. An office building casts a shadow that is 15 feet. If the building is 60 feet tall, how tall is the flagpole? An office building casts a 150-foot shadow at the same time a nearby pedestrian casts a 3-foot shadow. If the pedestrian is 6 feet tall, how tall is the office building?