因为 AD⊥BC且E为AC中亩皮点所以 DE=EA=EC所以 ∠C=∠EDC=∠BDF所以 ∠ABC=2∠BDF又因为 ∠ABC = ∠侍禅BDF+∠BFD所以 ∠老耐尘BDF = ∠BFD = ∠C所以 BD=BF△AEF∽△ABC