Do NowDo Now

Are these two figures similar?Are these two figures similar?

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90 °

40 °

50 °

90 °

ObjectiveObjective

Learn more tests for similarity. Learn more tests for similarity.

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HomeworkHomework

1.1. X = 10, Y = 10X = 10, Y = 10

3.3. X = 18, Y = 13.5X = 18, Y = 13.5

5.5. X = 27, Y = 14X = 27, Y = 14

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We found out that yesterday if we had 3 We found out that yesterday if we had 3 angles were congruent between two angles were congruent between two figures that they were similar. figures that they were similar.

AAA is our first test for similar triangles. AAA is our first test for similar triangles.

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The AAA Test for Similar Triangles

Lets try another test. Lets try another test.

Draw two triangles in your notebook. One Draw two triangles in your notebook. One side should be proportional to the other side should be proportional to the other and an angle created by that side should and an angle created by that side should be congruent in both. be congruent in both.

Are these two similar?Are these two similar?

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Test of Similar Triangles

The SAS Test for Similar TrianglesThe SAS Test for Similar Triangles

If a figure has two proportional sides that If a figure has two proportional sides that create the same (congruent) angle. Then create the same (congruent) angle. Then the triangles are similar. the triangles are similar.

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30

18

10

6

20°

20°

The SSS Test for Similar TrianglesThe SSS Test for Similar Triangles

This is just a new way to say that if all of This is just a new way to say that if all of the sides of a triangle are proportional the sides of a triangle are proportional then we know that they are similar. then we know that they are similar.

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16

520 20

4

5

AB BC AC= =

DE EF DF

A

B

CD

E

F

Lets Try This Together!Lets Try This Together!

Find all the missing anglesFind all the missing angles Find all the missing side lengthsFind all the missing side lengths

ABC BDAV : V

ExerciseExerciseAre these two figures similar? Are these two figures similar?

Can you label any more information?Can you label any more information?

A

B

C

D

E

F70°

70°70°

70°

45

9

12