Parallel Lines Cut By A Transversal

If two parallel lines are cut by a transversal, what happens?
[i]Move the X along the dotted line to adjust the angle of the transversal.[/i]
The following green lines are parallel.
The following red lines are not parallel.
What is the difference between the angles in the first screen versus the angles in the second screen?[br][br]What do you think causes that to happen?[br][br]Can you write your observations into an If ... then ... statement?
– Chelsea Coleburn

Información: Parallel Lines Cut By A Transversal