Congruent Triangles
You identified and used congruent angles.
• Name and use corresponding parts of
congruent polygons.
• Prove triangles congruent using the
definition of congruence.
Vocabulary
• If two geometric figures have exactly the
same shape and size, they are congruent.
• Un two congruent polygons, all of the
parts of one polygon are congruent to the
corresponding parts or matching parts of
the other polygon. These corresponding
parts include corresponding angles and
corresponding sides.
The Right Match
Congruent
Not congruent
A
D
F
C
B

E
Corresponding sides and angles
C
A
T
B
Corresponding Angles
S
R
Corresponding sides
A  R
C  T
AB
RS
B  S
BC
ST
AC
RT
H
B
A
C
K
J
The support beams on the fence form
congruent triangles. In the figure ΔABC 
ΔDEF, which of the following congruence
statements correctly identifies
corresponding angles or sides?
A.
B.
C.
D.
The phrase “if and only if” in the congruent polygon
definition means that both the conditional and its
converse are true. So, if two polygons are
congruent, then their corresponding parts are
congruent. For triangles, Corresponding parts of
congruent triangles are congruent, or CPCTC.
C PCTC