8th grade math please help.

Use the diagram that I attached below to complete this sentence:
Angle 2 and angle _____ are supplementary angles.

Also it would help me a lot if you explain why angle ____ is the correct answer!


8th Grade Math Please Help Use The Diagram That I Attached Below To Complete This Sentence Angle 2 And Angle Are Supplementary Angles Also It Would Help Me A Lo class=

Answer :

It’s angle 2 and 1 because they are across from each other! They share a straight angle that equals 180 degrees