Final answer:
Angle 1 and angle 3 are supplementary because angle 1 and angle 2 form a linear pair and angle 2 is congruent to angle 4.
Step-by-step explanation:
Let angle 1 and angle 2 form a linear pair, meaning that they are adjacent angles that add up to 180 degrees.
Since angle 2 is congruent to angle 4, angle 2 and angle 4 have the same measure and are congruent.
Since angle 1 and angle 2 form a linear pair and angle 2 is congruent to angle 4, we can conclude that angle 1 and angle 3 are supplementary because supplementary angles add up to 180 degrees.