已知:△ABC、△DEF中,∠A=∠D,AB=AC,DE=DF
求证:△ABC∽△DEF
证明:∵AB=AC,DE=DF
∴AB/AC=DE/DF=1
∴AB/DE=AC/DF(交换比例内项)
∵∠A=∠D
∴△ABC∽△DEF