论文部分内容阅读
在高中选修2-1第二章2.2.1《椭圆及其标准方程》中,有这样一道例题:如图1,设点A、B的坐标分别为(-5,0),(5,0)。直线PA,PB相交于点P,且它们的斜率之积是-4/9,求点P的轨迹方程。分析:设点P的坐标为(x,y),那么直线PA、PB的斜率就可以用含x,y的式子表示。由于直线PA、PB的斜率之积是-4/9,因此可以建立x,y之间的关系式6,得出点P的轨迹方程。
In the high school elective 2-1 second chapter 2.2.1 “elliptic and its standard equations”, there is such a case: Figure 1, set point A, B coordinates were (-5,0), (5,0 ). The straight lines PA, PB intersect at point P, and the product of their slopes is -4/9, and find the path equation for point P. Analysis: set the coordinates of the point P (x, y), then the slope of the line PA, PB can be expressed with x, y of the formula. Since the product of the slopes of the lines PA and PB is -4/9, the relationship 6 between x and y can be established, and the path equation of the point P can be obtained.