Download Angle-Angle Similarity of Triangles

Chapter 2 Similarity and
Dilations
LESSON 2 ANGLE-ANGLE SIMILARITY OF
TRIANGLES
Angle-Angle Similarity of Triangles
 You
can use Angle-Angle (AA) Similarity to test for
triangle similarity. If two angles of one triangle are
congruent to two angles of another triangle, then the
triangles are similar.
 When
you use indirect measurement to find unknown
lengths, you must first identify the corresponding sides
of the similar triangles and then correctly substitute
the known lengths into a proportion.
Angle-Angle Similarity of Triangles
Example 1 – Determine similarity.
The triangles are not similar because only one
pair of angles are congruent.
Try This
Example 2 – Use indirect measurement.
How tall is the flagpole?
ℎ
3.5
=
22
2
2ℎ = 77
ℎ = 38.5 ft
Try This
How tall is the taller building?
ℎ
50
=
50 12.5
12.5ℎ = 2500
ℎ = 200 ft
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 What
measures must be known in order to
calculate the height of tall objects using
shadow reckoning?
The length of the tall object’s shadow, the length of the
shadow of a nearby object and that object’s height.