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Dothanhphat
2 năm trước
Cho tam giác ABC (AB < AC) có ba góc nhọn, đường cao AH (H thuộc BC). Từ H kẻ HE vuông góc với AB (E thuộc AB) và HF vuông góc với AC (F thuộc AC). Chứng minh: a) AEH đồng dạng với tam giác AHB b) AE.AB = AH2 và AE.AB = AF.AC c) AEF dđồng dạng với tam giác ABC d) MB.MC = ME.MF, trong đó M là giao điểm của EF và BC.
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