4.3: Exploring Congruent Triangles

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4.3 Exploring Congruent Triangles

• pg. 196-203

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Definitions
Congruent triangles Triangles that are the same
size and the same shape.
Congruence Statement tells us the order in
which the
sides and
angles are congruent
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If 2 triangles are congruent

• The congruence statement tells us which parts of
  the 2 triangles are corresponding match up.

Means
3 Angles
3 Sides
ORDER IS VERY IMPORTANT
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Example
Meaning
?A ? ?T, ?R ? ?E, ?C ? ?F
AR ? TE, RC ? EF, AC ? TF
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Congruent Triangles
Example 2
Write the Congruence Statement
A
Z
B
C
Y
X
Example 3
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Example 3 Congruence Statement
Finish the following congruence statement ?JKL
? ?_ _ _
N
M
L
M
J
L
K
N
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Definition of Congruent Triangles (CPCTC)
Two triangles are congruent if and only if their
corresponding parts are congruent. (tells us when
Triangles are congruent)
Example
Are the 2 Triangles Congruent. If so write The
congruence statement.
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Ex. 2
Are these 2 triangles congruent? If so, write a
congruence statement.
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Transformations
Flip
Slide
Rotation
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Theorem 4-4 Congruence of triangles is
reflexive,
symmetric, and transitive.
What is the meaning of congruence of triangles
is reflexive.
How a congruence transformation would affect the
perimeter of a triangle.
Draw two noncongruent triangles that have the
same perimeter.
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Translation (down 5 over 4)
Does translation affect the congruence of
triangles?
Written as (x4, y 5)
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Rotation (90 degrees)
Does rotation affect the congruence of triangles?
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Reflection (over the y-axis)
Does reflection affect the congruence of
triangles?
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Assignment