

Course 3, Unit 3  Similarity and Congruence
Overview
In this unit, students develop understanding and skill in the use of
similarity and congruence relations to solve problems involving shape
and size. In each of the two lessons, students have many opportunities
to continue to develop skill and confidence in reasoning deductively
using both synthetic and coordinate methods.
Key Ideas from Course 3, Unit 3

Similarity: Conditions for polygons to be similar with special
attention to triangles and parallelograms are developed.

Congruence: Conditions for polygons to be congruent with
special attention to triangles and parallelograms are developed.

Centers of triangles: The three centers of triangles studied
in this unit are those formed by the perpendicular bisectors of the
sides, the angle bisectors, and the medians. (See pages 200203.)

Congruencepreserving transformations: The properties of
transformations and composites of transformations are reexamined
in this unit. These transformations were introduced in the coordinate
setting in Course 3 Unit 3, Coordinate Methods.
