giúp mk với xíu nữa học r Cho ΔDEF biết DE=6cm, DF=8cm, EF=10cm. a) Kẻ đường cao DK của ΔDEF. Tính DK, FK ? b) Vẽ phân giác trong EM của góc DEF (M∈DF). Tính độ dài các đoạn thẳng MD,ME,MF ? c) Chứng minh: MF=EF × tanDEM

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