Angles Formed by Parallel Lines Cut by a Transversal

In the applet below, [b]AB[/b] [b]|| CH[/b] (line [b]AB[/b] is parallel to line [b]CH[/b]). Line [color=#38761d][b]DE[/b][/color] is a [color=#38761d][b]transversal[/b][/color]. There are 8 angles formed at the intersections of the lines - do you see them?[br][br][list=1][*]Drag point A or B to change the location & direction of both parallel lines.[/*][*]Drag point D or E to change the location & direction of the transversal.[/*][/list][br]As you change the lines, pay attention to the measurements of the 8 angles that are marked. [br][br][list=1][*]Which angles are always the same size? [/*][*]Which angles are always supplementary (add up to 180°)?[/*][/list]
Parallel Lines cut by a Transversal

Information: Angles Formed by Parallel Lines Cut by a Transversal