Parallel Lines cut by a Transversal
Using translations, move the angles of a triangle to create a straight angle on line t. Given that the sum of the interior angles of a triangle must equal 180, what can you conclude the measure of a straight angle is? What do you notice about the angle relationships formed when parallel lines are cut by a third line? Is there an angle relationship when two non-parallel lines are cut by a third? Why do you think this is?