So AC and BD are parallel.

And because AC is perpendicular to AE, BD is perpendicular to BF.

So BD is perpendicular to AE.

So AE and BF are parallel.

This question examines the three-line octagon

Coincidence: The relative positions of ∠ 1 and ∠5, ∠2 and ∠6, ∠3 and ∠7, ∠4 and ∠8 are the same, which is called "congruence angle". The isosceles angle is shaped like the letter F.

Internal angles: ∠2 and ∠8, ∠3 and ∠5 cross each other and are all included, which is called "internal angle". The inner corner is shaped like the letter Z.

Internal angles on the same side: ∠ 2 and ∠ 5, ∠ 3 and ∠ 8 are on the same side of the section line, and they are all on the inside, which is called "internal angles on the same side". The inner corner on the same side is shaped like a letter u or a door frame.