Answer:
Step-by-step explanation:
1) m∠1 +m∠2 + m∠3 = m∠LAM (Angle addition postulate)
2) m∠1 + m∠2 + m∠3 = 180 (def. of straight angle)
3) y║z (Given)
4) ∠1 ≅ ∠5 (alternate interior angles theorem)
5) ∠3 ≅ ∠6 (alternate interior angles theorem)
6) Since m∠1 + m∠2 + m∠3 = 180
m∠5 + m∠2 + m∠6 = 180
Hence proved.
