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nguyen.khuyen.510
2 năm trước
Cho tam giác ABC vuông tại A, đường cao AH. a) Hãy chỉ ra các tam giác đồng dạng. Viết các tam giác này theo thứ tự các đỉnh tương ứng. b) Gọi I và K lần lượt hình chiếu của điểm H lên cạnh AB, AC. Chứng minh AI.AB = AK.AC mấy anh chị giải hộ em phần này nữa ạ c) Cho x+y+z=1 .Chứng minh rằng :x^2 + y^2+ z^2>=1/3
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