利用二次曲线准线解题

• 作 者: 邹振球
• 机 构: 江西省乐安二中!344300
• 出 处: 中学理科参考资料
• 发表日期: 1994年Z2期
• 关键词: 二次曲线 已知点 焦点距离 点坐标 圆相

圆锥曲线的准线是一条重要的直线,利用它解题,有许多方便之处。 例1.已知点A(1,0)和直线L: x=3,若动点M到点A的距离为m,到L的距离为n,且m+n=4,(1)求点M的轨迹,(2)过A作倾斜角为α的直线与M点的轨迹交于P、Q,设d=|PQ|=f(α),求f(α)的解析式。

The alignment of the conic curve is an important straight line, and there are many conveniences for solving problems using it. Example 1. Known point A(1,0) and straight line L: x=3, if the distance from the moving point M to point A is m, the distance to L is n, and m+n=4, (1) The trajectory of the point M, (2) cross the straight line with the inclination angle α and the trajectory of the point M intersect at P and Q, and set d=|PQ|=f(α) to find the analytical expression of f(α).