Answer:

The second question:

Answer:

This part of the extended data mainly examines the knowledge points of parallel line judgment:

Two straight lines are cut by a third straight line. If the isosceles angles are equal, two straight lines are parallel (the isosceles angles are equal and the two straight lines are parallel).

Judgement theorem of parallel lines;

(1) Two straight lines are cut by the third straight line. If the offset angles are equal, the two lines are parallel. (Internal dislocation angles are equal and two straight lines are parallel)

(2) Two straight lines are cut by a third straight line. If they are complementary to each other, the two straight lines are parallel. (The internal angles on the same side are complementary, and the two straight lines are parallel)

(3) If two straight lines are parallel to the third straight line, then the two straight lines are also parallel to each other. (If line A is parallel to line B and line B is parallel to line C, then line A is also parallel to line C) (equivalent replacement).