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nanana2000
2 năm trước
mình hứa sẽ vote 5 sao và chọn câu trả lời hay nhất :D Bài 3: Cho ABC vuông tại A. Từ K trên BC kẻ . Trên tia đối của tia HK lấy I sao cho HI = HK. Chứng minh : a. AB//HK b. Tam giác AKI cân c. góc BAK = góc AKI d. tam giác AIC = tam giác AKC Bài 4: Cho ABC vuông tại A. Lấy D trên cạnh BC, kẻ DH vuông góc với AC. Trên tia DH lấy E sao cho HE = HD. Chứng minh: a) BAD = ADE b) AD = AE c) AED = BAD Bài 5: Cho ABC cân tai A: AB = AC, M là trung điểm của BC trên tia đối của tia AM lấy điểm D sao cho AM = MD a) c/m: ABM =CDM b) AB // DC c) AM  BC d) Tìm đk của ABC để = 300
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