Download chapter 7: similar polygons

CHAPTER 7:
SIMILAR POLYGONS
7-4
A POSTULATE FOR SIMILAR
TRIANGLES
SIMILAR POLYGONS
Remember that we can prove two polygons
similar if we can show that:
1. Corresponding angles are congruent;
and
2. Corresponding sides are in proportion.
SIMILAR TRIANGLES
In the next two sections, we will identify and
utilize simpler methods in proving
triangles similar.
These methods include:
1. AA Similarity Postulate
2. SAS Similarity Theorem
3. SSS Similarity Theorem
POSTULATE 15
POSTULATE 15 AA Similarity Postulate
If two angles of one triangle are
congruent to two angles of another
triangle, then the triangles are similar.
Given: AC ║ BD
Prove: ∆AOC ~ ∆BOD
D
A
O
C
B
•
1. Given
2. If 2 ║ lines are cut by
a transversal, alternate
interior angles are ≡
3. AA ~ Postulate
Tell whether the triangles are similar or not
similar.
1.
1. Similar
2.
2. Similar
3.
3. Similar
FIND THE VALUE OF x & y
4.
4. 5 / 3
5
3
x
1
5.
5. x = 9 / 4,
x
8
y = 32 / 7
y
3
3
4
CLASSWORK/HOMEWORK
Classwork:
• Pg. 256, Classroom Exercises 2-10 even, 11
Homework:
• Pg. 257, Written Exercises 1-13