Transcript PP Section 4.1

Honors Geometry Section 4.1
Congruent Polygons
To name a polygon, start at any vertex and
go around the figure, either clockwise
or counterclockwise , and name the
vertices in order.
Example 1: Give two
(out of 12) possible
names for the hexagon
at the right.
DEMONS
MEDSNO
In simple terms, two polygons are
congruent if they have exactly the
same size and shape.
More formally, two polygons are
congruent iff their vertices can be
paired so that corresponding
angles and sides are congruent.
Example 2. List the congruent sides and angles
in the quadrilaterals below.
G   Y
E   S
O   A
N   T
GE  YS
GO  YA
ON  AT
EN  ST
When naming congruent polygons,
you must list the corresponding
vertices in order. This is known as a
congruence statement.
Example 3: Complete this
congruence statement using the
figure above:
quad GONE  quad ____
YATS
By looking at a congruence statement, you
can determine the pairs of corresponding
parts.
Example 4: Use the statement CAT  DOG
to fill in the blanks.
DO
G
ACT
To prove two triangles are
congruent using the definition of
congruent polygons, one must
show that all 6 pairs of
corresponding parts are congruent.
-----------------------------------------
A  N
AO  ON
AOV & NOV are rt. s
AOV  NOV
AVO  OVN
VO  VO
AVO  NVO
Given
Isosceles Triangle Theorem
Definition of Midpoint
Def. of Perpendicular Lines
Right Angle Theorem
Def. of Angle Bisector
Reflexive Property
Def. of cong. polygons
In subsequent sections, you will
see that it is possible to prove that
some triangles are congruent by
using only three pairs of congruent
parts!