Applied Geometry

Lesson: 9 – 3

Similar Triangles

Objective: Learn to use AA, SSS, and SAS similarity tests for triangles.

ReviewCongruent TrianglesTriangles whose sides and angles are

congruent.

Tests for congruenceSSSSASASAAAS

New – Tests for similarity

AA Similarity If two angles of one triangle are congruent to two corresponding angles of another triangle, then the triangles are similar.

SSS similarityIf the measures of the sides of a triangle are proportional to the measures of the corresponding sides of another triangle, then the triangles are similar.

SAS SimilarityIf the measures of two sides of a triangle are proportional to the measures of two corresponding sides of another triangle and their included angles are congruent, then the triangles are similar.

Determine whether the triangles are similar. If so, tell which similarity test is

used and complete the statement.

21

14

15

10

9

6

JMP SSS similarity

Determine whether the triangles are similar. If so, tell which similarity test is

used and complete the statement.

Not similar since SSS, SAS, or AA similarity tests prove true.

Determine whether the triangles are similar. If so, tell which similarity test is

used and complete the statement.

Not similar since sides are not proportional.

Find the value of x.

3

9

5x

453 x15x

Find the values of x & y

15

512

xx5180 x36

15

513

yy5195 y39

x

2

5.1

4.0

object

shadow

object

shadow

34.0 x5.7x

Flag pole is 7.5 meters tall.

Homework

Pg. 365 1 – 5 all, 6 – 22 E