Question

Show proof to prove the alternate interior angles theorem.
Given: segment A B is parallel to segment C D.
Prove: Alternate interior angles are congruent

Answer 1

By the parallel lines postulate, 2 is congruent to 6. But 2 is congruent to 4 (Vertical Angle Theorum). Then, by transitivity, 4 is congruent to 6. :-)

Answer 2

Oh my god thank you so much you are literally a lifesaver c:

Answer 3

No problem :-)

Answer 4

Also, would it change much if the Same-side interior angles are supplementary?

Answer 5

You mean, proving by supplementary angles? I guess not.