Technology Lab

Indirect Measurement

By: Munira Al-Essa, Shaikha Al-Roumi,

Answar Al-Sabah, Rayan Saeed

It’s spirit week at school and your team wants to decorate the light poles in the front of the building with strings of pennants in your school’s colors. The pennants are strung together and sold

by the foot. To know how many feet of pennants to buy, you need to know the height of the light poles.

1. The student who will be used for a comparison is 5 feet and 11 inches tall. The shadow cast by the student is 15 feet long. The shadow cast by the light pole is 88 feet long. You will use drawing tools to create and label a model of the student and a light pole.

Question

15 ft.5’11 ft.X

88 ft.

Work Out Equation= 520.08=x15 1. 5.91 15

X 882. 5.91*88=520.8 and 15*x=? Because we don’t know how tall the light post is.3. 520.08=x15 ÷15 ÷15 x=34.67

AnswerWord FormThe light pole is 34.67 ft. tall. X=34.67 ft.

Indirect Measurement ContinuedTechnology Lab

6. Find the ratio of height to shadow to determine the height of the light.The ratios you constructed should look like this. Remember to change all units to inches.

5 feet 11 inches h feet 15 feet 88 inches

=

SO in inches

= 71 inches h inches

180 inches 1056 inches

In equation180h=74976

H=416.53

1. There are six light poles in the front of school. Will you be able to buy enough flags for each of the poles if they cost $0.80 per foot and you have $155.00 to spend on the project?Yes and $150.2 will be left over.

Think&Discuss

? ??

1. Complete the following ratios to compute the height of themissing side of these right triangles.a. 5 h 20 120So 600=h20 h=30

b. H 7 9 21So 63=21h h=3

TryThis! =

=

2. On a separate piece of paper, draw an illustration and show the ratio for a redwood tree that is 200 feet in height that casts a shadow 500 feet long.

200 ft

500 ft

Indirect MeasurementHomework and Practice

1. H 39 6 13

1. Use similar triangles to find the height of the building.

2. So 234=13h

H=16

6 ft

13 ft

H

36 m

1. 3 4 h 36

2. Use similar triangles to find the height of the tree

2. So 108=4h

H=27

36 mH

3m

4 m

3. A lamppost casts a shadow that is 15 yards long. A 3-foot-tall mailbox casts a shadow that is 5 yards long. How tall is the lamppost?

1.h 15

3 5

2. So 40=5h H=8

15 Yards

H3 ft 5 Yards

4.An 8-foot-tall statue stands in the park and casts a shadow that is 16 feet long. A dog stands next to it and is 3 feet tall. How long is the dog's shadow?

1. h 3 16 8 2. So 48=8h H=6

8 ft

16 ft

3 ft

h

5. A building casts a shadow that is 420 meters long. At the same time, a person who is 2 meters tall casts a shadow that is 24 meters long. How tall is the building?

1. h 420 24 2 2. So

840=2hH=420

420 mh

24 m2 m

6. On a sunny day around noon, a tree casts a shadow that is 12 feet long. At the same time, a person who is 6 feet tall standing beside the

tree casts a shadow that is 2 feet long. How tall is the tree?

1. 6 2 h 12

2. So 72=2h H=36

2 ft6 ft12 ft

h

7. A pole casts a shadow that is 21 feet long. A 3-feet-tall child standing next to the pole casts a shadow that is 9 feet long. How tall is the pole?

1. 3 9 h 21

2. So 63=9h H=7

21 ft

h 3 ft

9 ft

8. Jeremy has two trophies next to each other sitting in the window of his room. His football trophy is 7 inches tall and his basketball trophy is13 inches tall. As the light shines in, the basketball trophy’s shadow

measures 26 inches. How long is the football trophy’s shadow?

1. h 7 26 13

2. So 182=13h H=14

7 inches

26 inches13 inches

h