在三角形ABC中,AB=AC,点D,E,F分别在AB,BC,AC边上,已知DE=DF,角EDF=角A,找出图中相似的三角形,并证明

①△ABC∽△DEF证明：∵AB=AC,DE=DF∴AB/DE=AC/DF又∵∠A=∠EDF∴△ABC∽△DEF（SAS）②△DBE∽△ECF证明：∵△ABC∽△DEF∴∠DEF=∠B∵∠CEF+∠BED=180°-∠DEF ∠BDE+∠BED=180°-∠B∴∠CEF=∠BDE∵AB=AC∴∠B=...（2）求证ab/bc=be/cf∵△ABC∽△DEF
∴AB/DE=BC/EF
转化为AB/BC=DE/EF
∵△BDE∽△CEF

∴BE/CF=DE/EF
∴AB/BC=BE/CF