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Unit 4 Congruent Triangles ~ Lesson Objective
To recognize congruent figures
and their corresponding parts.
Congruent Figures
Congruent Polygons: Congruent polygons are polygons that have
corresponding sides that are congruent and corresponding angles
that are congruent.
Ex. Of corresponding:
C correspond s to R
B corresponds to Q
AX corresponds to PY

B  Q C  R A  P X  Y
AX  PY

XB  YQ
BC QR
ACBX  PRQY
CA  RP
Congruent Figures
To be congruent, figures must have the same:
 Shape
 Size
 You can slide, flip or turn them so that one fits
exactly over the other
Congruent Figures
ABC  QRS. List the congruent corresponding parts.
Congruent Figures
Given that the following pentagons are congruent, find the
value of B.
C
A
R
W
132°

B
E
95°
S
P
T
D
Congruent Figures
92°
40°
Theorem 4-1: If two angles of one triangle are congruent to
two angles of another triangle, then the third angles are
congruent.
C  F
Since A  D


and B  E
then C F
Congruent Figures
Decide whether the triangles are congruent. Justify!
E
3
B
4
C
3
A
4
D
Proving Triangles Congruent
Given : PS  PQ
Prove : PQR  PSR
QR  SR
Q  S
QPR  SPR
Statements
Reasons
1. PS  PQ ; QR  SR
1.
2.
2. Reflexive Property
3. Q  S ;QPR  SPR
3.
4. QRP  SRP
4.
5.
5.
Definition of
 polygons