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aenokhkh
2 năm trước
Cho tam giác ABC kẻ đường cao BD và CE ( D thuộc AC, Ethuộc AB ) . BD và CE cắt nhau tại H  a) Chứng minh : AE.AB = AC.AD và BH . BD + CH.CE= BC^2 b) Cho góc AED = 40 độ . Tính số đo góc HBC  c) Trên các đoạn thẳng BD và CE lần lượt lấy 2 điểm I và K sao cho góc AIC = AKB = 90 độ  . Chứng minh tam giác AIK cân  Giúp mình với , mình cần gấp
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