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phunganpp
2 năm trước
Cho ∆ABC vuông tại B . Gọi D là trung điểm của cạnh AC . Trên tia đối của tia DB lấy điểm E sao cho DB = DE . Chứng minh : a, ∆ABD = ∆CDE b, góc AEC là góc vuông
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