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nhanhotrong456
2 năm trước
Cho đường tròn (O) ,đường kính AB, E là 1 điểm thuộc (O). E không trùng vớiA,B.Gọi M,N lần lượt là trung điểmAE, BE. Tiếp tuyến của (O) tại B cắt ON kéo dài tại D a) tính OD biết OB=5, EB=6 b)chứng minh BDE là tam giác cân c)chứng minh DE là tiếp tuyến của (O) tại E d)chứng minh MONE là hình chữ nhật
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