笛卡尔发明直角坐标系的目的是为了使几何问题通过代数计算的方法来解决.为了考查学生综合运用能力,通常中考压轴题把点、直线、三角形等图形作为运动图形,让学生通过数学建模与方程组、不等式(组)建立联系,来实现几何问题用代数方法来解决的目的,尤其是平面内有两点固定,另两点运动来确定一个特殊四边形的位置,综合运用数形结合、分类讨论、 The purpose of Cartesian invention of Cartesian coordinate system is to solve geometric problems through algebraic calculations. In order to examine students’ comprehensive abilities, the final exam questions are usually taken as the motion graphics of points, lines, triangles, etc., so that students can use mathematical modeling. Establish relations with equations and inequalities (groups) to solve the geometric problem by using algebraic methods to solve the problem. In particular, there are two fixed points in the plane, and the other two points determine the position of a special quadrilateral. Classified discussion,