Question 1119263
angle 2 = angle 3.


if angle 2 is supplementary to angle 1, then angle 2 + angle 1 = 180.


since angle 2 is equal to angle 3, you can replace angle 2 with angle 3 in the equation of angle 2 + angle 1 = 180 to get:


angle 3 + angle 1 = 180.


that makes angle 3 and angle 1 supplementary.