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nguyenhuynh2032001
2 năm trước
Cho ΔABC có đường cao AH. Kẻ HE ⊥ AB tại E, kéo dài HE lấy EM=EH. Kẻ HF⊥AC tại F, kéo dài HF lấy FN=FH. Gọi I là trung điểm của MN. Chứng minh rằng : a, AB là trung trực của MH và AC là trung trực của HN b,ΔAMN cân
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