Question

如图,在△ABC中,∠ABC＜∠ACB＜∠BAC,∠BAC和∠ABC的外角平分线AE、bd分别与bc、ca的延长线交于e

Answer 1

设∠ABC=X,

∠D=∠BAD=∠ABC+∠AEB=2∠ABC=2X

∠DBA=180°-2∠D=180°-4X

∠ABF=2∠DBA=360°-8X

∠ABC=180°-∠ABF=8X-180°=X

X=180°/7

∠2=∠1=∠3

∠BAC=180-2∠3=180-4X=540°/7