Page 81 - Math Course 3 (Book 2)

Congruent Triangles
Mo. 9

Lesson 3 Key Concept

KEY CONCEPTS: Definition of Congruent Triangles(CPCTC)

1. Name and label corresponding parts of Two triangles are congruent if and only if their
congruent triangles. corresponding parts are congruent.
2. Identify congruence transformations.

THEOREM 9.4
MO. 9 - L3a

Identify and Label Congruent Properties of Triangle Congruence

Triangles Congruence of triangle is reflexive, symmetric, and
transitive.

Reflexive △JKL ≅ △JKL
Vocabulary A-Z

Let us learn some vocabulary Symmetric If △JKL ≅ △PQR, then △PQR ≅ △JKL

If △JKL ≅ △PQR, and △PQR ≅ △XYZ,
congruent triangle Transitive then △JKL ≅ △XYZ
Triangles that are the same size and shape are
congruent triangles. K Q
L R
B F

J P

C G Y
A E Z

△ABC is congruent to △EFG
X

congruence transformations
If you slide, flip, or turn a triangle, the size and
shape do not change. These three transformations
are called congruence transformations.
D’
E

Turn to
rotation
D
F F’ E’
△DEF is congruent to △D’E’F’

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