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npthuan2009
2 năm trước
Cho góc xOy nhọn, trên tia Ox lấy điểm A và trên tia Oy lấy điểm B sao cho OA=OB. Qua A, vẽ đường thẳng d1 vuông góc với Ox, cắt Oy tại C. Qua B, vẽ đường thẳng d2 vuông góc với Oy, cắt Ox tại D. Gọi I là giao điểm của d1 và d2 . a) Chứng minh rằng: ΔOAC=ΔOBD. b) Chứng minh rằng: ΔDIC cân. c) Chứng minh rằng: OI là tia phân giác của góc AIB.
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