2. Main Idea and New Vocabulary Example 1: Use Shadow Reckoning
Example 2: Use Indirect Measurement
Lesson Menu

3. Solve problems involving similar triangles.
indirect measurement
Main Idea/Vocabulary

4. Use Shadow Reckoning
FLAGPOLES A flagpole near a city parking area casts a 22-foot shadow. At the same time, a 3.5-foot-tall parking meter casts a 2-foot shadow. How tall is the flagpole?
Example 1

5. 22 • 3.5 = 2 • h Find the cross products. 77 = 2h Multiply.
Use Shadow Reckoning
Shadow Height
flagpole
parking meter
flagpole
parking meter
22 • 3.5 = 2 • h Find the cross products.
77 = 2h Multiply.
Divide each side by 2.
38.5 = h
Answer: The flagpole is 38.5 feet tall.
Example 1

6. SWINGS At the same time a 5-foot tall fence casts a 7-foot shadow, a nearby swingset casts a 16.8 shadow. How tall is the swingset?
A. 6 feet
B. 12 feet
C feet
D feet
Example 1 CYP

7. Use Indirect Measurement
LAKES The two triangles shown in the figure are similar. Find the distance across the lake.
Example 2

8. Use Indirect Measurement
Write a proportion using the corresponding sides.
10 • 5 = (10 + d) • 2 Find the cross products.
50 = d Multiply. Subtract 20 from each side.
Then divide each side by 2.
15 = d
Answer: The distance across the lake is 15 meters.
Example 2

9. LAKES The two triangles shown in the figure are similar
LAKES The two triangles shown in the figure are similar. Find the distance across the lake.
A. 12 feet
B. 27 feet
C. 30 feet
D. 45 feet
Example 2 CYP