作DF//AC,交AB于F∵AC=BC,∠C=90°∴∠CAB=∠B=45°∵DF//AC∴∠DFB=∠CAB=45°∴∠DFB=∠B=45°∴DF=BD∵DE⊥AB∴△DEF是等腰直角三角形∴DE=EF∵AD平分∠BAC∴∠CAD=∠FAD∵DF//AC∴∠CAD=∠ADF∴∠FAD=∠ADF∴AF=...