Find the number of diagonals that can be drawn in an n-side polygon.
ans: n(n-3) / 2
Please give the explanation....Thank you very much!!
maths and stat(combination)
2010-06-15 10:01 pm
回答 (1)
2010-06-15 10:09 pm
✔ 最佳答案
There are nC2 ways to choose any 2 vertices. Out of these, n are to be excluded as they are the sides of the polygon. The number of diagonals = nC2 – n
= n(n – 1)/2 – n
= n(n – 3)/2
2010-06-24 12:32:35 補充：
對角線要選擇其中2個頂點
但nC2是包括該POLYGON的邊.....所以要減走多邊形的邊才是答案
收錄日期: 2021-04-13 17:18:33
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