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Thaovy73
2 năm trước
Cho tam giác ABC vuông ở A. Kẻ AH vuông góc với BC. Gọi P, Q là các điểm đối xứng của H qua AB và AC a) Chứng minh: P và Q đối xứng qua A b) Cho HP cắt AB tại I, HQ cắt AC tại K. Gọi M, N là trung điểm của BH và CH. Chứng minh: tứ giác MNKI là hình thang vuông c) Với điều kiện nào của thì tứ giác MNKI là hình chữ nhật d) Chứng minh: MI + NK không đổi khi BC cố định còn A di động sao cho vuông ở A.
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