Triangle Similarity Postulates
are triangles that have the same size and shape.
Congruent triangles
?
Similar triangles
?
have the same shape but different sizes.
Similar Triangles
?
Congruent Triangles
?
How do we know when triangles are similar?
Their corresponding angles have to be
Their corresponding sides have to be
2
5
4
1
2.5
2
proportional
?
congruent
?
The triangles shown are similar. Find the ratio ofthe corresponding sides of the triangles.Simplify to a whole number if possible.
3
7.5
6
1
2.5
2
31
=
The triangles shown are similar. Find the ratio ofthe corresponding sides of the triangles.Simplify to a whole number if possible.
3
7.5
6
1
2.5
2
6
2
=
The triangles shown are similar. Find the ratio ofthe corresponding sides of the triangles.Simplify to a whole number if possible.
3
7.5
6
1
2.5
2
7.52.5
=
These triangles are similar.
Solve for x.
2
5
x
20
5x = 
x
2
Solve
x = 
=
5
These triangles are similar.
Solve for x.
10
6
15
x
10x =
x
6
Solve
x = 
=
10
There are three ways to prove triangles similarDrag and drop the correct postulate abbreviation. Some drop values will not be used. 
Side Side Side
Side Angle Side
Angle Angle
SSS
?
SAS
?
AA
?
ASA
AAS
HL
Complete the similarity statement. 
AA Similarity Postulate:If two angles of one triangle are congruent to two anglesof another triangle, the triangles are similar.
R
T
S
F
∆RST ~ ∆
E
G
The triangles shown in the picture are: 
))
10
congruent by SAS
congruent by ASA
similar by SAS
similar by SSS
similar by AA
5
))
The triangles shown in the picture are: 
13
12
congruent by SAS
congruent by SSS
similar by SAS
similar by SSS
similar by AA
5
5
12
13
The triangles shown in the picture are: 
10
6
congruent by SAS
congruent by SSS
similar by SAS
similar by SSS
similar by AA
5
3
The triangles shown in the picture are: 
10
)
14
congruent by SAS
congruent by SSS
similar by SAS
similar by SSS
similar by AA
12
5
7
6
((
SAS Similarity Postulate: If two sides of one triangle are proportional to two sides of another triangle, and the angles between thesides are congruent, then the triangles are similar.
Simplify each ratio.
8
6
12
9
12 8
9
6
=
=
9
3
SSS
?
4
6
1
3
1
SAS
?
2
AA
?
12
3
Students who took this test also took :

Created with That Quiz — a math test site for students of all grade levels.