Understand why vertical angles are congruent using properties of supplementary angles.
Discover that corresponding angles are congruent.
Discover the relationship between same-side interior and alternate interior angles when two parallel lines are cut by a transversal.
Use angle relationships to find missing angles when two parallel lines are cut by a transversal.
Explain why the sum of the measures of the interior angles of a triangle is 180 degrees.
Apply the exterior angle theorem to find missing angles of a triangle.