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vuthithuyhl3
2 năm trước
Bài 5 :Cho ∆ABC vuông cân tại A, AM là trung tuyến của ∆ABC. Lấy điểm K thuộc tia đối của tia MA sao cho MK= MA. Kẻ đường thẳng d bất kỳ qua A, Kẻ BH ⊥ d, CE ⊥ d ( H, E ⊥ d ). a)Chứng minh ∆AMB = ∆ KMC và KC // AB. b)Hỏi ∆ AKC là tam giác gì? Vì sao? c)Chứng minh: BH = AE và BH + CE = HE. d)Lấy Q, P lần lượt là trung điểm của AC, CK. Gọi BQ giao AM tại F, AP giao BC tại D. Chứng minh DF  AB. Bài 6 : 1) Cho tam giác ABC cân tại A và góc A = 100 độ . Gọi O là một điểm nằm trên tia phân giác của góc C sao cho góc CBO = 30 độ. Tính góc CAO ? giúp mik làm 2 bài này với mik cảm ơn và sẽ cho 5 sao
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