我们在求解涉及二次函数的综合问题时,经常会遇到这样一类问题,即求动点坐标,使得该点与另外两固定点所构成的三角形为直角三角形或等腰三角形.在遇到这类问题时,许多学生会感到比较棘手,无从下手.其实借助勾股定理,灵活运用两点之间的距离公式,问题就会变得比较简单.公式(两点之间距离公式)如图1,点P(x_1,y_1)、点Q(x_2,y_2)为平面直角坐标系中的任意两点,则有 When solving comprehensive problems involving quadratic functions, we often encounter such a problem that the coordinates of the moving point are such that the triangle formed by this point and the other two fixed points is a right-angled triangle or an isosceles triangle. In fact, with the help of Pythagorean theorem, the problem of using the distance formula between two points becomes simpler. The formula (the distance between two points) is shown in Figure 1 , Point P (x_1, y_1), point Q (x_2, y_2) is any two points in the plane rectangular coordinate system, then there is