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nguyenthevinh68
2 năm trước
Cho tam giác ABC vuông tại A ( AC > AB ) , đường cao AH và trung tuyến AM : a ) Chứng minh tam giác ABC đồng dạng với tam giác HBA và AB²= BH BC b ) Qua B vẽ đường thẳng song song với AC cắt AH tại D. Chứng minh HA.HB - HC.HD. c ) Qua B vẽ đường thẳng vuông góc với AM cắt AC tại E. Chứng minh AE .AC = BH.BC d ) Gọi I , K lần lượt là trung điểm của BD và AC ; S là giao điểm của hai đường thẳng AB và CD . Chứng minh 4 điểm S , I , H , K thẳng hàng
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