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Warm-Up
Geometry
Proving Triangles are
Congruent
Learning Outcomes!
I
will be able to use given information to
recognize which congruence postulate
can be used to prove that two triangles
are congruent.
In your notes!
 Draw
 Then,
a triangle but specify two lengths.
using a protractor, find the
measures of the angles inside of the
triangle.
 In
your notes.
 Are
these triangles congruent?
Side-Side-Side
Which triangles are
congruent?
ABC
ACE
ECD
DCB
Are there other ways to prove
congruence?
 Using
a piece of trace paper copy the
two side lengths you measured and the
angle between them.
 Do
you get congruent triangles?
 What
do you think this congruence
postulate is called?
Side-Angle-Side
Congruence Postulates
 SSS:
Side-Side-Side Congruence
 SAS: Side-Angle-Side Congruence
 What
other congruence postulates might
exist?
 AAA
 ASA
 AAS or SAA
 SSA
Angle-Angle-Angle
 What
 Are
are the measure for angles x and y?
these congruent triangles?
Angle-Angle-Angle
 Angle-Angle-Angle
can be used to show
that triangles are similar, but it does not
show that they are congruent.
Angle-Side-Angle
 What
does Angle-Side-Angle mean?
What parts are congruent?
 From
the triangle you made in your notes
earlier. Copy two angles and the side
length between onto a piece of trace
paper.
 Complete
 Are
your triangle.
these triangles congruent?
Angle-Side-Angle
Angle-Angle-Side
 Can
we prove that these two angles are
congruent?
 Think-Pair-Share
Angle-Angle-Side
Side-Side-Angle
 Draw
this picture along with me in your
notes.
 Side-Side-Angle
does not show that
triangles are congruent.
What ways can we show that
triangles are congruent?
 SSS
 SAS
 ASA
 AAS
Homework
 Pg.
216: 2-19, 41-46 and Pg. 223: 8-13
 Pg. 216: 20, 22-25 and pg. 224: 19-22, 3237