本文拟介绍与切线有关的圆锥曲线的两个性质及推论.定理1若圆锥曲线的任意一条切线与两条定切线分别相交,则两交点与该圆锥曲图1定理1图线的同一个焦点连线的夹角为定角.证不妨设圆锥曲线为椭圆C,如图1,其方程为x2a2+y2b2=1(ab0),右焦点F(c,0),两条定切线与C分别切于两定点A( In this paper, two properties and inferences of tangent-related conic curves are introduced. Theorem 1. If any tangent of a conic curve intersects with two fixed tangents, the two points of intersection are the same focal point as the theorem 1 line of the conic diagram. The angle of the line is a fixed angle. The proof may be to set the conic curve to an ellipse C, as shown in Figure 1. The equation is x2a2+y2b2=1(ab0), the right focus F(c,0), and the two fixed tangents and C are respectively Cut at two fixed points A (