若没其他条件,只能∠AEC=∠D+1/2*∠BAD
∠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
∠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
前边回答挺好。