Page 85 - Math Course 3 (Book 2)

Triangle Congruence Postulates
Mo. 9

Lesson 4 F I

KEY CONCEPTS:
G
1. Use the SSS Postulate to test for triangle
congruence
2. Use the SAS Postulate to test for triangle
congruence.

E H
MO. 9 - L4a

Triangle Congruence: Given: EI ≅ FH; FE ≅ HI; G is the midpoint of both
EI and FH.
SSS Postulate Prove: ΔFEG ≅ ΔHIG

Proof:
POSTULATE 9.1 Statements Reasons
1. EI ≅ FH; FE ≅ HI; G is the 1. Given
Side-Slide-Side Congruence midpoint of both EI and FH.

If the sides of one triangle are congruent to the 2. FG ≅ HG; EG ≅ IG 2. Midpoint Theorem
sides of a second triangle, then the triangles are 3. ΔFEG ≅ ΔHIG 3.SSS
congruent.

Abbreviations: SSS
Z
SSS on the Coordinate Plane
B
Example

A C COORDINATE GEOMETRY
△ABC ≅ △ZXY Y X Determine whether ΔWDV ≅ ΔMLP for D(–5, –1),
V(–1, –2), W(–7, –4), L(1, –5), P(2, –1), and
M(4, –7). Explain.
Let’s Begin Use the Distance Formula to show that the
corresponding sides are congruent.

Use SSS in Proofs

Example

ENTOMOLOGY

The wings of one type of moth form two triangles.
Write a two-column proof to prove that ΔFEG ≅ ΔHIG
if EI ≅ FH, FE ≅ HI, and G is the midpoint of both EI

and FH.

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