Download The two figures are similar. 1) Write a similarity statement. 2) Find

GEOMETRY NOTES
Lesson 6.4
Prove Triangles Similar by AA
Review for the Lesson
Rode2011
5
I
The two figures are similar.
1) Write a similarity statement.
Q
F
7
T
3.6
7.1
5
10
H
6
S
G
2) Find the scale factor.
R
Lesson 6.4
Objectives: Students will be able to (SWBAT):
• use the AA similarity postulate to prove triangles similar
Postulate 22 - Angle-Angle (AA) Similarity Postulate
If angles of one triangle are congruent to two angles of
another triangle, then the triangles are similar.
B
B
E
∆ABC~∆DEF
D
F
A
A
34
o
56
o
C
C
1) Show the two triangles above are
similar and write a similarity
statement.
Using the AA Similarity Postulate
Example 1
Determine if the two triangles are similar. If they are, write a
similarity statement. Explain your reasoning.
K
ANGLE:
∠TSR ≅ ∠KNP
Since they are both right angles
݉∠TRS = 90 − 27 = 63o
or
݉∠TRS = 180 − 90 − 27 = 63o
63
o
P
N
T
27
ANGLE: ∠TRS ≅ ∠NKP
Since they both measure 63o.
R
o
S
Therefore similar due to AA Similarity Postulate
Similarity Statement: ∆RST ~∆KNP
Page 1
D
2) Show the two triangles are similar
and write a similarity statement.
Example 2
Show that the two triangles are similar.
A
1
50
E
B
50
D
2
o
o
C
Example 3
Show that the two triangles are similar.
P
C
R
Q
B
Self – Assessment
In the table below give the objectives for the lesson and then list what we did to meet the objective. Finally, rate
your understanding of the material (Excellent, Very good, Good, Poor) and what you specifically need to do next.
Objective
What did we do that
addressed that objective?
Rate your understanding of the material and your next
steps.
Page 2