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vuongquocchomeo2004
2 năm trước
Bài 1. Cho tam giác ABC, AH vuông góc với BC, AH = 12 cm, AB = 15 cm, CH = 16 cm. a) Tính độ dài BH, AC. b) Tam giác ABC có là tam giác vuông không? Vì sao? Bài 2. Cho tam giác ABC cân tại A. Kẻ AH vuông góc BC . Từ H kẻ HD vuông AB. Chứng minh rằng: a) AH là tia phân giác của góc A. b) HD = HE. Bài 3. Cho tam giác ABC có A=90 độ, AB =8cm,AC=6cm. a) Tính BC. b) Trên cạnhAC lấy điểm E sao cho AE = 2cm. Tính EB. c) Trên tia đối của tia AB lấy điểm D sao cho AD = AB. Chứng minh∆BEC=∆DEC.
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