1964年IMO的第5題
Five points are given in the plane. Among the lines that connect these five points, no two coincide and no two are parallel or perpendicular. Through each point we construct an altitude to each of the other lines. What is the maximal number of intersection points of these altitudes (excluding the initial five points)?
我算出的答案是310，但我不知道要如何構造出例子，有人有其他答案嗎?
Five points are given in the plane. Among the lines that connect these five points, no two coincide and no two are parallel or perpendicular. Through each point we construct an altitude to each of the other lines. What is the maximal number of intersection points of these altitudes (excluding the initial five points)?
我算出的答案是310，但我不知道要如何構造出例子，有人有其他答案嗎?
回應
longlong
Re: IMO的問題
2010-07-18 20:05vic526tor
Re: IMO的問題
2010-07-18 21:07longlong
Re: IMO的問題
2010-07-20 04:33連結裡的答案有包括最初的 5 個點
所以它答案是 315
vic526tor
Re: IMO的問題
2010-07-20 20:19