Page 87 - Math Course 3 (Book 2)

Triangle Congruence Postulates

MO. 9 - L4b Let’s Begin

Triangle Congruence:

SAS Postulate
Use SAS in Proofs

Vocabulary A-Z Example

Let us learn some vocabulary Write a flow proof.

included angle R S

the angle formed by two sides of the triangle.

The included angle of The included angle of
BA and BC in △ABC is DF and DE in △FDE is
ABC. FDE. T
Q
B RQ || TS
D Given:
F RQ ≅ TS

Prove: △QRT ≅ △STR
C
A E

RQ || TS RQ ≅ TS RT ≅ TR
POSTULATE 9.1 Given Given Reflexive Property

Side-Angle-Side Congruence

If two sides and the included angle of one triangle ∠QRT ≅ ∠STR
are congruent to two sides and the included angle Alternate interior ∠s are ≅.
of another triangle, then the triangles are congruent.

Abbreviations: SAS △QRT ≅ △STR
SAS
B D
F Identify Congruent Triangles

Example
C E
A Determine which postulate can be used to prove
△ABC ≅ △FDE that the triangles are congruent. If it is not possible
to prove that they are congruent, write not possible.

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