下面是老师在课堂上让我们讨论的一道题目:已知⊙O:x~2+y~2=r~2,P(x_0,y_0),判断直线l:x_0x+y_0y=r~2与圆⊙O:x~2+y~2=r~2的位置关系.我们通过比较圆心到直线的距离d=r~2/(x_0~2+y_0~2)~(1/2)与r的大小,得出了如下结论:(1)当P(x_0,y_0)在圆外时,l与⊙O相交; The following is a teacher in the class let us discuss a subject: Known ⊙ O: x ~ 2 + y ~ 2 = r ~ 2, P (x_0, y_0), to determine the line l: x_0x + y_0y = r ~ 2 and the circle ⊙O: x ~ 2 + y ~ 2 = r ~ 2. By comparing the distance from the center to the straight line d = r ~ 2 / (x_0 ~ 2 + y_0 ~ 2) ~ Size, we come to the following conclusions: (1) When P (x_0, y_0) is outside the circle, l intersects with ⊙O;