cho tam giác ABC cân tại A trên cạnh AB lấy điểm D trên cạnh AC lấy điểm E sao cho AD=AE gọi M là gioa điểm của BE và CD, chứng minh a)BE=CD b) tam giác BMD= tam giác CME c) AM là tia phân giác của góc BAC d) gọi Ilà trung điểm của BC. Chứng minh A,M,I tHẲNG HÀNG

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