Big Idea

Understand why vertical angles are congruent using properties of supplementary angles.

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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.