Name _______________________________________ Date __________________ Class __________________
LESSON
7-3
Reteach
Triangle Similarity: AA, SSS, and SAS
Angle-Angle (AA)
Similarity
Side-Side-Side (SSS)
Similarity
Side-Angle-Side (SAS)
Similarity
If two angles of one triangle
are congruent to two angles of
another triangle, then the
triangles are similar.
If the three sides of one
triangle are proportional to the
three corresponding sides of
another triangle, then the
triangles are similar.
If two sides of one triangle are
proportional to two sides of
another triangle and their
included angles are
congruent, then the triangles
are similar.
ABC  DEF
ABC  DEF
ABC  DEF
Explain how you know the triangles are similar, and write a similarity
statement.
1.
2.
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
3. Verify that ABC  MNP.
________________________________________
________________________________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
7-22
Holt Geometry
Name _______________________________________ Date __________________ Class __________________
LESSON
7-3
Reteach
Triangle Similarity: AA, SSS, and SAS continued
You can use AA Similarity, SSS Similarity, and SAS Similarity to solve problems.
First, prove that the triangles are similar. Then use the properties of similarity to
find missing measures.
Explain why ADE  ABC and then find BC.
Step 1
Prove that the triangles are similar.
A  A by the Reflexive Property of .
AD 3 1
 
AB 6 2
AE 2 1
 
AC 4 2
Therefore, ADE  ABC by SAS .
Step 2
Find BC.
AD DE

AB BC
3 3.5

6 BC
Corresponding sides are proportional.
Substitute 3 for AD, 6 for AB, and 3.5 for DE.
3(BC)  6(3.5)
Cross Products Property
3(BC)  21
Simplify.
BC  7
Divide both sides by 3.
Explain why the triangles are similar and then find each length.
4. GK
5. US
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
7-23
Holt Geometry
Name _______________________________________ Date __________________ Class __________________
LESSON
7-3
Reading Strategies
Use a Graphic Aid
Use the flowchart to determine, if possible, whether the following pairs of
triangles are similar. If similar, write AA , SSS , or SAS  —the postulate
or theorem you used to conclude that they are similar. If it is not possible
to conclude that they are similar, write no conclusion.
1.
2.
________________________________________
3.
________________________________________
4.
________________________________________
5.
________________________________________
6.
________________________________________
7.
________________________________________
8.
________________________________________
________________________________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
7-26
Holt Geometry
Name _______________________________________ Date __________________ Class __________________
LESSON
7-3
Practice B
Triangle Similarity: AA, SSS, SAS
For Exercises 1 and 2, explain why the triangles are similar and write
a similarity statement.
1.
2.
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
For Exercises 3 and 4, verify that the triangles are similar. Explain why.
3. JLK and JMN
4. PQR and UTS
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
________________________________________
For Exercise 5, explain why the triangles are
similar and find the stated length.
5. DE
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
7-20
Holt Geometry
Name _______________________________________ Date __________________ Class __________________
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
7-20
Holt Geometry