1、∵CD⊥AB,BE⊥AC∴∠ADC=∠AEB=90°∵∠BAE=∠CAD(同角)∠ADC=∠AEB=90°BE=CD∴△ABE≌△ACD(AAS)∴AD=AE,AB=AC∴AB-AD=AC-AE那么BD=CE2、∵∠ADC=∠AEB=90°即∠ADO=∠AEO=90°∴RT△AOD、RT△AOE中AD=AE,OA=OA∴RT△AOD≌RT△AOE(HL)∴∠1=∠2∴AO平分∠BAC
⊥AC,垂足富哦发育、irir
用三角形全等证