With some examples in plane geometry, the author indroduces how to use Desargues theorem to simplify the proofs of problems of collinearpoints and concurrent lines.
利用代沙格定理及其逆定理 ，对平面几何的几个共线点和共点线的问题给出简捷的证法。
2
Hayes solves the problem of determining whether three points in a plane are collinear.
Hayes解决了如何确定一个平面上的三个点是否在一条直线上的问题。
3
Orbits of this type can be positioned near collinear libration points, and for simplicity it is adequate to take linear terms into consideration in the control process.