Dilations, Similarity and Slope

Understand the similarity of two-dimensional figures using dilations.

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What students learn

In this lesson, students understand similarity using physical models, transparencies, or geometry software.

Describe the effect of dilations, translations, rotations, and reflections on two- dimensional figures using coordinates.
Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations, and dilations; given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.
Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.