Similarity and Basic Properties of Similarity - 8.3 - Lessons 8 and 9

Student Outcomes

1. Students know the definition of similar and why dilation alone is not enough to determine similarity. (Lesson 8)

2.  Given two similar figures, students describe the sequence of a dilation and a congruence that would map one figure onto the other. (Lesson 8)

3. Students know that similarity is both a symmetric and a transitive relation. (Lesson 9)

Lesson Review

- We know that similarity is defined as the sequence of a dilation, followed by a congruence.

- To show that a figure in the plane is similar to another figure of a different size, we must describe the sequence of a dilation, followed by a congruence (one or more rigid motions), that maps one figure onto another.

Lesson Summary

• Similarity is defined as mapping one figure onto another as a sequence of a dilation followed by a congruence (a sequence of rigid motions). 
• The notation that triangle ABC ~ A'B'C', means that they are similar.