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ecudellbiet123
2 năm trước
Cho ΔABC có CD là trung tuyến. Điểm E ∈ AC sao cho $\frac{AE}{AC}$= $\frac{2}{9}$. Cho biết AB = 18cm, AC = 27cm, BC = 30cm. Tính độ dài DE.
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