Chapter 8 Lesson 3

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Chapter 8 Lesson 3

• Objective To apply AA, SAS, and SSS similarity.

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Name the postulate or theorem you can use to
prove the triangles congruent.
1.                            
SSS
2.                            
SAS
3.                        
ASA
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Name the SIMILARITY postulate or theorem you can
use to prove the triangles congruent.
1.                            
AA
2.                            
SAS
3.                        
SSS
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Example 1 Finding Lengths in Similar Triangles
 Explain why the triangles are similar. Write a
similarity statement. Then find DE.
Because vertical angles are congruent.
?ABC ?EBD by the SAS Theorem.
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Example 2 Finding Lengths in Similar Triangles
Find the value of x in the figure.
                 
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Indirect Measurement is when you use similar
triangles and measurements to find distances that
are difficult to measure directly.
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Example 3 Indirect Measurement
Geology Ramon places a mirror on the ground 40.5
ft from the base of a geyser. He walks backwards
until he can see the top of the geyser in the
middle of the mirror. At that point, Ramon's eyes
are 6 ft above the ground and he is 7 ft from the
image in the mirror. Use similar triangles to
find the height of the geyser.
?HTV ?JSV
The geyser is about 35 ft. high.
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Example 4 Indirect Measurement
In sunlight, a cactus casts a 9-ft shadow. At the
same time a person 6 ft tall casts a 4-ft shadow.
Use similar triangles to find the height of the
cactus.
X
6
4
9
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Assignment
Page 435 10-21, 23, 28-39