证：由题可知，∠BDO = ∠CEO = 90°，∠BOD = ∠COE（对角），且OB = OC∴△BOD ≌ △COE（AAS）∴OD = OE∵∠ADO = ∠AEO = 90°，DO = EO，AO为公共边，∴△ADO≌△AEO（HL）∴∠1 = ∠2
先证明dob相似于eoc
