利用数形结合解题,是公认的一种好方法,但在构图时却有优劣之分,只有灵活地构图,选择最优图解题,才能使解题更直观、简捷.椭圆和圆是我们利用数形结合解题时经常用的图形,但有些题目从形式上看可利用椭圆进行解答,实际上可通过变形利用圆来解答,从而可使解答更简单,举例如下. It is a well recognized method to solve the problem by the combination of number and form, but there are merits and demerits in composition. Only the flexible composition and selection of the optimal solution can make the problem more intuitive and simple. Is a graph that we often use to solve problems by using a combination of numbers, but some of the questions can be answered in the form of ellipses, which can be effectively solved by using circles to make the solution easier. Examples are as follows.