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20 tháng 11 2015

Công thức tính số đường thẳng là:

\(\frac{n.\left(n-1\right)}{2}\) (N là số điểm)

Vậy tạo được: \(\frac{8.\left(8-1\right)}{2}=28\) đường 

7 tháng 12 2015

45

19 tháng 11 2017

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