过D作BE的平行线DG交AC于G,则EG/GC=BD/DC=2/3,EG=2EC/5 因EF//DG EF/DG=AE/AG=AE/(AE+EG)=AE/(EC/3+2EC/5)=AE/(11EC/15)=15/11*AE/EC=15/11*1/3=5/11 EF=5DG/11
同样,因DG//BE DG/BE=DC/BC=DC/(BD+DC)=DC/(2DC/3+DC)=3/5 BE=5DG/3
BE/EF=(5DG/3)/(5DG/11)=11/3
过D作BE的平行线DG交AC于G,则EG/GC=BD/DC=2/3,EG=2EC/5 因EF//DG EF/DG=AE/AG=AE/(AE+EG)=AE/(EC/3+2EC/5)=AE/(11EC/15)=15/11*AE/EC=15/11*1/3=5/11 EF=5DG/11
同样,因DG//BE DG/BE=DC/BC=DC/(BD+DC)=DC/(2DC/3+DC)=3/5 BE=5DG/3
BE/EF=(5DG/3)/(5DG/11)=11/3