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sweetlove.thuthuy
2 năm trước
Bài tập) Cho Δ ABC cân tại $ A $. Kẻ phân giác AD ( $ D ∈ $ BC). Trên tia đối của tia AB lấy điểm $ E $ sao cho AE $ = $ AB. Trên tia phân giác của ∠CAE lấy điểm F sao cho AF $ = $ BD. Chứng minh rằng: $ a $) AD $ ⊥ $ BC $ b $) AF // BC $ c $) EF = AD $ d $) Các điểm E, F, C thẳng hàng.
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