CD=2BE
延长BE交CA延长线于F.
∵∠FCE=∠BCE CE=CE ∠CEF=∠CEB=90°
∴⊿CEF≌⊿CEB
∴FE=BE
∵∠DAC=∠CEF=90°
∴∠ACD+∠F=∠ABF+∠F=90°
∴∠ACD=∠ABF
∵∠ACD=∠ABF AC=AB ∠CAD=∠BAF=90°
∴⊿ACD≌⊿ABF
∴CD=BF
∴CD=2BE
CD=2BE
延长BE交CA延长线于F.
∵∠FCE=∠BCE CE=CE ∠CEF=∠CEB=90°
∴⊿CEF≌⊿CEB
∴FE=BE
∵∠DAC=∠CEF=90°
∴∠ACD+∠F=∠ABF+∠F=90°
∴∠ACD=∠ABF
∵∠ACD=∠ABF AC=AB ∠CAD=∠BAF=90°
∴⊿ACD≌⊿ABF
∴CD=BF
∴CD=2BE