Only spend about 30 seconds here![br]Lines a and b are parallel. They are cut by transversal c. Drag the blue points on c to move the transversal. [br][br]Think:[br]How does this affect the angles? [br]Which angles are always congruent? [br]Which angles are always supplementary?[br][br]Note: Do not allow the blue points to fall inside the parallel lines or the angles will disappear!