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Chapter 7 Section 2: Similar Polygons
Word Definition Similar
Figures
Similar
Polygons
Extended
Proportions
Scale Factor
Scale
Drawing
Scale
Example 1: Understanding Similarity
ΔMNP ~ ΔSRT a) What are the pairs of congruent angles?
b) What is the extended proportion for the ratios of corresponding
sides?
Example 2: Determining Similarity
Are the polygons similar? If they are, write a similarity statement and give the scale
factor.
Example 3: Using Similar Polygons
ABCD ~ EFGD. What is the value of x?
Example 4: Using Similarity
Your class is making a rectangular poster for a rally. The poster’s design is 6 in. high
by 10 in. wide. The space allowed for the poster is 4ft high by 8 ft wide. What are the
dimensions of the largest poster that will fir in the space?
Word Definition Angle-Angle
Similarity
(AA~)
Postulate
If two angle of one triangle are congruent to two angle of another triangle
then the triangles are similar.
Side-AngleSide Similarity
(SAS~)
Postulate
If an angle of one triangle is congruent to an angle of another triangle, and
the sides that include the two angles are proportional, then the triangles
are similar.
Side-Side-Side If the corresponding sides of two triangles are proportional, then the
Similarity
triangles are similar.
(SSS~)
Postulate
Indirect
Measurement
Chapter 7 Section 3: Proving Triangles Similar
Example 1: Using AA ~ Postulate
Are the two triangles similar? How do you know?
A) ΔRSW ~ ΔVSB B) ΔJKL ~ ΔPQR
Example 2: Verifying Triangle Similarity
Are the triangles similar? If so, write a similarity statement for the triangles.
A)
B)
Example 3: Finding Lengths in Similar Triangles
Before rock climbing, Darius wants to know how high he will climb. He places a mirror
on the ground and walks backward until he can see the top of the cliff in the mirror.
What is the height of the cliff?
PRACTICE