Lesson 2: 7-2: Similar Polygons

For what types of transformations are the preimage and the image similar but not necessarily congruent?
2. What transformation changes the size of the figure?
3. IF two figures are congruent, can you conclude they are similar?

Similar Polygons
Similarity
Transformation
Scale Factor

G.SRT.2
Given two figures, use the definition of similarity transformations to decide if they are similar; explain using similarity transformations the meaning of similarity for triangles as the equality of all corresponding pairs of angles and the proportionality of all corresponding pairs of sides.

Two polygons are similar if there is a similarity transformations or combination of a similarity transformation and one or more rigid transformations that maps one polygon onto the other. Similarity transformations are dilations and the rigid motions (translations, reflections, and rotations).

People often customize their computer desktops using photos, centering the images at their original size or stretching them to fit the screen. This second method distorts the image because the original and new images are not geometrically similar.

Students approaching grade level can be given practice problems in small groups to work with other students or directly with the teacher.
Students beyond grade level can make deeper connections by finding the scale factor between two polygons given their perimeter.

Formative Assessment

Textbook in class

Access online textbook and resources through class link.