取DE中点O，连接AO，∵四边形ABCD是平行四边形，∴AD∥BC，∴∠DAB=180°-∠ABC=105°，∵AF⊥BC，∴AF⊥AD，∴∠DAE=90°，∴OA=12DE=OD=OE，∵DE=2AB，∴OA=AB，∴∠AOB=∠ABO，∠ADO=∠DAO，∠AED=∠EAO，∵∠AOB...