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quachmanhha
2 năm trước
Cho tam giác ABC có AM là trung tuyến. Vẽ Mx , My lần lượt là phân giác của các góc BMA , CMA . Mx , My lần lượt cắt AB , AC tại D , E . a) Chứng minh DA/DB=AM/BM b) Chứng minh DE//BC c) Cho AB/AB = 6/8. Tính S tam giác ADE/ S tam giác ABC
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