1. Main Idea and New Vocabulary Key Concept: Similar Figures
Example 1: Identify Similar Figures
Example 2: Find Missing Measures
Example 3: Find Missing Measures
Lesson Menu

3. Solve problems involving similar figures.
corresponding sides
corresponding angles
indirect measurement
Main Idea/Vocabulary

4. Key Concept

5. Identify Similar Figures
Which rectangle is similar to rectangle FGHI?
Example 1

6. Identify Similar Figures
Find the ratios of the corresponding sides to see if they are the same.
Rectangle LMNO
Rectangle ABCD
Rectangle QRST
Not Similar
Not similar
Similar
Answer: So, rectangle ABCD is similar to rectangle FGHI.
Example 1

7. Which triangle is similar to triangle ABC?D.
Example 1 CYP

8. If ΔABC ~ ΔDEF, find the length of .
Find Missing Measures
If ΔABC ~ ΔDEF, find the length of
Example 2

9. Let x represent the length of . Then substitute.
Find Missing Measures
Write a proportion.
Let x represent the length of Then substitute.
3x = 4.5(11) Find the cross products.
3x = 49.5 Simplify.
x = 16.5 Divide each side by 3.
Answer: The length of is 16.5 centimeters.
Example 2

10. If rectangle ABCD ~ rectangle GHIJ then find the length of .
A. 12 cm
B. 8.5 cm
C. 3.5 cm
D. 3 cm
Example 2 CYP

11. 71(15) = 42.6x Find the cross products. 1,065 = 42.6x Simplify.
Find Missing Measures
PALM TREES At a certain time of day, a cabbage palm tree that is 71 feet high casts a shadow that is 42.6 feet long. At the same time, a nearby flagpole casts a shadow that is 15 feet long. How tall is the flagpole?
Write a proportion.
71(15) = 42.6x Find the cross products.
1,065 = 42.6x Simplify.
25 = x Divide each side by 42.6.
Answer: The tree is 25 feet tall.
Example 3

12. SHADOWS An oak tree that is 30 feet tall casts a shadow that is 10 feet long. At the same time, Joe, who is 6 feet tall also casts a shadow. How long is his shadow?
A. 2 ft
B. 9 ft
C. 18 ft
D. 20 ft
Example 3 CYP