Khan Academy
Khan Academy: Geometry: Angles Formed by Parallel Lines and Transversals
Identifies which angles are congruent when parallel lines are cut by a transversal. [7:07]
Khan Academy
Khan Academy: Geometry: Angles (Part 3)
Identifies and defines the types of angles formed by parallel lines cut by a transversal and the relationship of their measures. Discusses Triangle Sum Theorem. [9:48]