there are 10 points on a plane ,and any arbitrary three points are not in a straight line.

题目

there are 10 points on a plane ,and any arbitrary three points are not in a straight line.
segments or not,linking any two points .In order to make sure that any point in these ten points can arrive at any other points by the linking line segments,how many line segments between two points should be linked at least?
不是翻译，是做题，不用英语回答。

答案

一个面上有10个点,其中任意三个点不在一条直线上.
两个点之间可以用线段连接.
为了使平面上的任意一个点可以通过连接线段到达另外任意一个点,最少应该有多少条连接线段?
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9条线段,保证所有的的点都连起来就可以.