Question

初一数学题，大家帮帮忙啊！！跪求，急啊，今晚就要！！

在四边形ABCD中,AE是∠BAF的角平分线,CF是∠ECD的角平分线,AE‖CF,求∠AEC与∠D的关系

Answer 1

若没其他条件，只能∠AEC=∠D+1/2*∠BAD

Answer 2

∠E=1/2∠BAD+∠B

∠E=180-1/2∠DCB

1/2∠BAD+∠B=180-1/2∠DCB

∠BAD+2∠B=360-∠DCB

2∠B=360-∠DCB-∠BAD

=∠B+∠D

∠B=∠D

所以∠AEC-∠B=1/2∠DAB

∠AEC=∠D+1/2∠DAB

Answer 3

∠E=1/2∠BAD+∠B
∠E=180-1/2∠DCB
1/2∠BAD+∠B=180-1/2∠DCB
∠BAD+2∠B=360-∠DCB
2∠B=360-∠DCB-∠BAD
=∠B+∠D
∠B=∠D

∠AEC-∠B=1/2∠DAB

∠AEC=∠D+1/2∠DAB

Answer 4

前边回答挺好。