Download 7.3 similar triangles.notebook

7.3 similar triangles.notebook
1/10/17 ­ Warm Up Problem
A movie theater screen has a width of 45 ft and a length
of 25 ft. Which TV screen is a similar rectangle to the
movie screen?
27 in
20 in
36 in
36 in
7.3 similar triangles.notebook
Section 7.3 - Proving Triangles Similar
Goals: Identify similar triangles
Use similar triangles to solve problems
Are these similar triangles?
7.5
5
10
To tell if triangles are similar, you do not need to check
to see if all corresponding angles are congruent and all
corresponding sides proportional.
There are 3 shortcuts you can use to determine
similarity: AA~, SAS~, and SSS~
7.3 similar triangles.notebook
Proving Triangles Similar - Shortcuts
Postulate 7­1 Angle ­ Angle Similarity (AA~)
If two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar.
7.3 similar triangles.notebook
Are the triangles similar by AA?
Explain why or why not.
N
F
S
o
45
R
70 M
T
o
L
G
H
D
A
C
B
E
K
J
7.3 similar triangles.notebook
Proving Triangles Similar - Shortcuts
Theorem 7­1 Side ­ Angle ­ Side Similarity (SAS~)
If one angle of one triangle is congruent to one angle of another triangle and the sides including the two angles are proportional, then the triangles are similar.
L
H
10
5
J
F
G
3
K
6
7.3 similar triangles.notebook
Proving Triangles Similar - Shortcuts
Theorem 7­2 Side ­ Side ­ Side Similarity (SSS~)
If the corresponding sides of two triangles are proportional, then the triangles are similar.
Y
B
4
3
A
5
12
9
C
X
15
Z
7.3 similar triangles.notebook
Can each pair of triangles be proven similar by SAS or
SSS? Write a similarity statement if they are similar.
7.3 similar triangles.notebook
Assignment:
pg. 455
(1-3)
(7-12)
(18-21)