CE:BE=AD:AC
∵EF∥AB
∴CE:BE=CF:AF
∵AF=EF
∴CE:BE=CF:EF ①
∵∠ADC=∠FEC=90º,∠CAD=∠EFC
∴ΔADC≌ΔEFC
∴CF:EF=AD:AC ②
∴由①、②得 CE:BE=AD:AC