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Binhbo
2 năm trước
Bài 5: Cho DEF vuông tại D, có đường cao DK. Từ K kẻ KP DE (P DE), KQ DF (Q DF) a) Chứng minh tứ giác DPKQ là hình chữ nhật. b) Gọi I là trung điểm của KF, H là điểm đối xứng với D qua I. Chứng minh tứ giác DKHF là hình bình hành. c) Gọi O là giao điểm của DK và PQ. Chứng minh O là trực tâm của tam giác DEI. d) Tam giác DEF cần có điều kiện gì thì DPKQ là hình vuông ? e) Tính diện tích DEF và diện tích tứ giác DKHF, biết DF = 8cm, EF = 10cm, DP = 4cm?
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