These are the different types of angles formed when 2 parallel lines are crossed by a transversal.
This is a video on what happens when parallel lines get intersected by a transversal
Source: http://www.schooltube.com/search/?term=Angles+formed+by+parallel+lines+and+transversals
This is a video where the author (Khan) walks you through what happens when parallel lines are cut by a transversal.
Source: www.khanacademy.org
