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hoangbang702
2 năm trước
MÔN: HÌNH HỌC – TOÁN 9 Đề bài: Cho AABC nhọn ( AB< AC) nội tiếp đường tròn (O) có hai đường cao BE và CF cắt nhau tại H. a) Chúng minh: tứ giác AEHF và BCEF nội tiếp. (4 điểm) b) Chúng minh: HE.HB = HF.HC . (2 điểm) c) Vẽ đường kính AM của đường tròn (O). Gọi điểm N là giao điểm của AM và EF . Chứng minh: AEF = AMC và AM 1 EF tại N. (2,5 điểm) d) Gọi 1 là trung điểm đoạn BC . Chứng minh: I là trung điểm đoạn HM . (1,5 điểm) НЕТ giải hộ m nha
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