Parallel Lines Cut by a Transversal

When a transversal crosses two parallel lines, it creates 8 angles with special relationships: Corresponding angles: Same position at each intersection → Equal Alternate interior angles: Opposite sides of transversal, between parallels → Equal Alternate exterior angles: Opposite sides, outside parallels → Equal Co-interior (same-side interior) angles: Same side, between parallels → Supplement…

Example: Lines l parallel m are cut by a transversal. One angle is 65°. Find all 8 angles.

If the SAT tells you lines are parallel, immediately look for corresponding or alternate interior angles — they're equal. If it asks you to PROVE lines are parallel, show that corresponding angles are equal or alternate interior angles are equal.