- Angle-sum theorem of a triangle. ( Students should be able to explain why the interior angles of a triangle add up to 180 degrees. Students should be able to use the interior angle sum of a triangle theorem to find missing angle measures in a triangle.)
- Angle Relationships: Supplementary, complementary, vertical, corresponding, alternate interior, alternate exterior.
- Use algebraic equations and angle relationships to find missing angle measures (requires a review of solving algebraic equations)
- Interior angle sum of polygons. (Students should be able to arrive at a rule for finding the sum of the interior angles of any polygon, and use the theorem to find missing angle measures in any polygon. )
- similarity of triangles (by AA - Angle Angle theorem): Determine whether or not two triangles are similar based on two corresponding pairs of interior angles. Use proportions to find missing sides of similar triangles.