1. If ∠B=∠DCG, which two straight lines are parallel can be judged? Why?

2. If ∠DCG=∠D, which two straight lines are parallel can be judged? Why?

3. If ∠DFE+∠D= 180 degrees, which two straight lines are parallel can be judged? Why?

If this is the question, the answer is;

1, AE//DC, because the congruence angle is equal and the two lines are parallel.

2.BG//AD, because the internal dislocation angles are equal, two straight lines are parallel.

3.AD//EF, because the internal angles on the same side are complementary, the two straight lines are parallel.