tren nua mat phang cho n diem phan biet, trong do co dung 3 diem thang hang. Qua 2 diem ta ve mot doan thang. biet so doan thang la 171. Tim n
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Nếu ko có 3 điểm nào thẳng hàng thì vẽ đc 45 đường thẳng và 90 tia
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18 tháng 11 2018
a) Có tất cả n(n-1):2 đoạn thẳng
b)Ta có 55.2 = 110
Mà 110=11.(11-1)
-> n=11 Vậy n=11
Học tốt nhé bạn kich, cho mình đi