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duongphat
2 năm trước
cho tam giác ABC vuông tại A , đường cao AH. Gọi I,K theo thứ tự là trung điểm của HA HC. Qua C kẻ đường thẳng vuông góc với BC cắt IK tại E. chứng minh a, IK song song AC và IK = 1^2 AC
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