In triangle ABC, BD = CE, DF = EF, ab = AC

In triangle ABC, BD = CE, DF = EF, ab = AC

Do DM ‖ AC hand BC to M
∴∠E=∠FDM,∠FCE=∠FMD
∵DF=EF
∴△CEF≌△MDF(AAS)
∴DM=CE
∵BD=CE
∴DM=BD
∴∠B=∠DMB
∵DM∥AC
∴∠DMB=∠ACB=∠B
∴AB=AC