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Cho hình vuông ABCD có E là trung điểm AD và F là trung điểm của BC. A) Chứng minh EBFD là hình bình hành.B) Gọi K là giao điểm của AF và BE. Chứng minh KA=KE.C) Một đường thẳng bất kì cắt đường thẳng AB tại M; cắt đường thẳng EF tại N; cắt đường thẳng CD tại P. Chứng minh N là trung điểm của MP.
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