Respuesta :

[tex]\bar{AB}\cong\bar{CD}[/tex][tex]AB+BC\cong BC+CD[/tex][tex]AC\cong BD[/tex]

If

[tex]AE\parallel BF[/tex]

Then

[tex]m\angle A\cong m\angle B[/tex]

If

[tex]CE\parallel DF[/tex]

Then

[tex]m\angle C\cong m\angle D[/tex]

So, by ASA congruency rule

[tex]\text{AEC}\cong BFD[/tex]