解析几何中有一些较为复杂的求轨迹方程问题,往往可以归结为求已知曲线的伴随曲线方程。所谓伴随曲线,可以这样定义: “对于已知平面曲线C上的各点M,取同一平面上的点P和它对应,即M→P,当点M在曲线C上移动时,点P一般也要伴随着M而变动,设P点的轨迹为C°,则称C°为C的伴随曲线,并称M和P互为相伴点。”(引自《中学数学中的伴随曲线及其方程的求法》,见《中学数学》 In analytical geometry, there are some more complex problems of finding the trajectory equation, which can often be attributed to finding the adjoint curve equations of known curves. The so-called adjoint curve can be defined as follows: “For each point M on the known plane curve C, take point P on the same plane and it corresponds to it, that is, M→P. When point M moves on curve C, point P is generally It also changes with M. Let the trajectory of P point be C°, then call C° the companion curve of C, and call M and P each other as companion points.” (quoted from “Adjoint curve in high school mathematics” For the Formulation of Equations, see “Middle School Mathematics”