我们知道,对于二次曲线f(x,y)=0(圆、椭圆)和平面内一点P0(x0,y0),有如下充要条件。(1)若P0(x0,y0)在曲线f(x,y)=0的内部f(x0,y0)0.(2)若P0(x0,y0)在曲线f(x,y)=0的内部过P0(x0,y0)的直线L恒与曲线f(x,y)=0相交。如果充分利用“点在曲线内部”这一充要条件和性质解题,不仅求解 We know that for the conic f (x, y) = 0 (circle, ellipse) and the plane of a point P0 (x0, y0), the following necessary and sufficient conditions. (1) If P0 (x0, y0) is within f (x0, y0) 0 of curve f (x, y) (P0, (x0, y0)) of the interior intersects the curve f (x, y) = 0. If we take full advantage of the “necessary conditions inside the curve” and the nature of the problem-solving, not only solution