Question

AD是三角形ABC的中线,

Answer 1

∵∠ADB=2∠ADC,∴∠ADC=60°,又∵CE⊥AD,∴∠ECD=30°,在RT△CDE中,CD=2ED,又∵∠BDF=∠CDE,BF⊥AD于F,所以BD=2DF,又∵BD=CD.∴FD+ED=BD=EF.