Under this topic you can study in detailed about following facts:
If two parallel lines are cut by a transversal, then each pair of corresponding angles has equal measure.
If two parallel lines are cut by a transversal, then each pair of alternate angles has equal measure.
If two parallel lines are cut by a transversal, then each pair of interior angles on the same side of the transversal are supplementary.
All these Facts / Properties are proved with diagrams in the above provided links.
