计算几何算法，包括以下内容：目录
㈠ 点的基本运算
1. 平面上两点之间距离 1
2. 判断两点是否重合 1
3. 矢量叉乘 1
4. 矢量点乘 2
5. 判断点是否在线段上 2
6. 求一点饶某点旋转后的坐标 2
7. 求矢量夹角 2
。。。。。。(Catalog
A bit of basic arithmetic
1. the distance between two points on the plane is 1
2. determine whether the two points coincide 1
3. vector product 1
4. vector dot product 2
5. whether the judgment point is on the line 2
6. ask for a bit of the coordinates after a point of rotation 2
7. vector angle 2)