* Write and interpret congruence statements * Use properties of congruent triangles * Prove triangles congruent using the definition of congruence

1. Congruent Triangles
The student is able to (I can):
• Write and interpret congruence statements
• Use properties of congruent triangles
• Prove triangles congruent using the definition of
congruence.

2. Geometric figures are congruent if they are
the same sizesizesizesize and shapeshapeshapeshape. Corresponding
angles and corresponding sides are in the
same position in polygons with the same
number of sides.

3. congruent
polygons
Two or more polygons whose corresponding
angles and sides are congruent.
E D
R A
P
C
Corresponding
Angles
∠R ≅ ∠C
∠E ≅ ∠A
∠D ≅ ∠P
Corresponding
Sides
≅RD CP
≅RE CA
≅ED AP
Thus, ΔRED ≅ ΔCAP.

4. Note: In a congruence statement, the
order of the vertices indicates the
corresponding parts.
Example: Name the corresponding angles if
polygon SWIM ≅ polygon ZERO.
∠S ≅ ∠Z; ∠W ≅ ∠E; ∠I ≅ ∠R; ∠M ≅ ∠O
Example: Name the corresponding sides if
ΔTAN ≅ ΔCOS.
TA CO; AN OS;NT SC≅ ≅ ≅

5. Example: Write a congruence statement
for the congruent triangles below.
C M
X J
B
F
ΔCMX ≅ ΔFBJ

6. Example: Given ΔTEA ≅ ΔCUP, find x
From the congruence statement, we know
that TE ≅ CU. So,
2x — 2 = 6
2x = 8
x = 4
T
E A
C
U
P
2x — 2 53º53º53º53º
6
10