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待定系数法是中学数学中的一种重要方法。本文就平面解析几何的特点,归纳总结出应用待定系数法时确定系数的几种方法。1.直接利用条件确定待定系数例抛物线 y~2=2px 的内接正三角形的一个顶点在原点,三边上的高都通过抛物线的焦点,求此三角形外接圆的方程。解如图1,设 A 点的坐标为(x_1,y_1),则 y_1=(?)因此 A 点的坐标为(x_1,(?)),由对称性得 B 点的坐标为
To be determined coefficient method is an important method in high school mathematics. In this paper, the characteristics of plane analytic geometry are summarized, and several methods to determine the coefficients when applying undetermined coefficient method are summarized. 1. Direct use of conditions to determine the coefficient to be determined Example parabola y ~ 2 = 2px of the inscribed equilateral triangle vertex at the origin, the three sides are high through the focus of the parabola, find the triangle circumcircle equation. Solution As shown in Figure 1, suppose the coordinate of point A is (x_1, y_1), then the coordinate of point A is (x_1, (?)), Then the coordinate of point B