Intro to G.6

Congruent Triangles

1

Congruent Figures2

Congruent figures are two figures that have the same size and shape.

IF two figures are congruent THEN they have the same size and shape.

IF two figures have the same size and shape THEN they are congruent.

Two figures have the same size and shape IFF they are congruent.

Congruent Triangles - CPCTC

3

If ABC PQR

A

A P B Q C

B PQ BC Q C P

R

R A R

CPCTC: Corresponding Parts of Congruent Triangles are Congruent

Two triangles are congruent IFF their corresponding parts (angles and sides) are congruent.

BC

A

QR

PA ↔ P; B ↔ Q; C ↔ R

Vertices of the 2 triangles correspond in the same order as the triangles are named.

Corresponding sides and angles of the two congruent triangles:

≡

≡

=

=

│

│

Congruent Triangles

____

____

____

AB

BC

AC

ZY

YX

ZX

Lesson 4-2: Congruent Triangles 4

B

A

C

X Y

Z

≡ ≡=

=

│ │

∆ABC ______

A ____ Z

B _____

C ______

Y

X

∆ ZYX

∆ABC ∆XYZ

Note:

ZY

5

When referring to congruent triangles (or polygons), we must name corresponding vertices in the same order.

R

AY

S

UN

S

U

N

R

A

YSUN RAY

Also NUS YAR

Also USN ARY

Example…………

Example ………

6

M

O

N

TA SR

UP

E

1. Pentagon MONTA Pentagon PERSU

2. Pentagon ATNOM Pentagon USREP

3. Etc.

If these polygons are congruent, how do you name them ?