CK-12 Foundation
Ck 12: Interactive Geometry: 4.2 Theorems About Lines and Angles
Consider two parallel lines that are intersected by a transversal, and when it crosses the two others, many different angle pairs are formed. See the special properties of the angle pairs in this interactive.
Math Open Reference
Math Open Reference: Corresponding Angles
Learn about corresponding angles with this resource which offers detailed explanations and examples. Subjects covered include parallel and non-parallel cases. Links to related topics.