What do you notice about the angles formed when two parallel lines are cut by transversal

If two parallel lines are cut by a transversal, then each pair of consecutive interior angles is supplementary.

If two parallel lines are cut by a transversal, then each pair of alternate exterior angles is congruent.

If two parallel lines are cut by a transversal, then each pair of alternate interior angles is congruent.

If two parallel lines are cut by the transversal, then each pair of corresponding angles is congruent.

When two parallel lines are cut by a transversal, some congruent angles are formed. For example, the angles above the parallel lines and on the same side with respect to the transversal, vertical angles, exterior corresponding angles, etc.

The basic idea is that when a transversal cuts across two parallel lines, many pairs of congruent angles are formed.