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SRT.2 Similarity Notes 2

SRT.2 I can use similarity conditions, congruent angle pairs and proportional sides, to determine if two figures are similar.

Similarity Conditions: 1. Congruent Angle Pairs 2. Proportional Sides

SRT.2 Conditions of Similarity: 1. Congruent Angle Pairs 2. Proportional Sides

SRT.2 Conditions of Similarity: 1. Congruent Angle Pairs  2. Proportional Sides

Similarity Conditions: Congruent Angle Pairs

Similarity Conditions: Congruent Angle Pairs

Using Similarity Conditions

Do you think the two triangles are similar? Explain why or why not.

Congruent Angle Pairs & Proportional Sides

If the triangles are similar, use proportional sides to determine the length of side AC

Congruent Angle Pairs & Proportional Sides

If the triangles are similar, use proportional sides to determine the length of side ED

Proportional Sides

Proportional Sides

Proportional Sides

Write three proportions to represent which sides are proportional to which. Express your three proportions like this: with the three sides of one triangle in the numerators positions and the proportional three sides of the other triangle in the denominator positions.

the Cross-Produce Rule

Triangles Largest side opposite Largest Angle, Smallest Side opposite Smallest Angle

Triangles  Largest side opposite Largest Angle, Smallest Side opposite Smallest Angle

Similarity Condition: Proportional Sides

If two figures are similar, then every side has a proportional side And if every side of a figure has a proportional side to another figure, then the figures are similar. Note: Every side of a figure must be proportional to one side of the similar figure.
Image

Testing triangles for similarity: proportional sides

If any two triangle are similar, then you should be able to write THREE proportions, like this  Test each pair of triangle, by testing the proportions of each pair. Since you will be testing 3 pairs of triangle, you will need to test 9 proportional statements (three for each pair) Which of the triangles above are similar?

For extra help, you may want to work through Khan Academy's Introduction to Similar Triangles