Question

(1/2)在Rt三角形ABC中,角ACB=90度,AC=BC,D为BC的中点,CE垂直AD于点E,BF//AC交CE的延

Answer 1

〈ACD=〈CBF=90°,CE⊥AD,〈ECD+〈CDE=90°,〈CAD+〈CDA=90°,〈CAD=〈BCF,△CAD≌△BCF,BF=CD,CD=BD,BF=BD,〈DBG=〈CAB=〈FBG=45°,BG=BG,△DGB≌△FGB,〈FGB=〈DGB,〈DGB+〈FGB=180°,∴DF⊥AB