我们知道,对圆锥曲线上的定点张直角的弦恒过一定点,这一结论已散见于各种数学刊物,如[1],[2].2009年北京、山东高考试卷中的解析几何问题又分别涉及了椭圆和双曲线对中心张直角弦的问题.这启发我们探究圆锥曲线对平面上的一般位置的定点张直角弦的性质.本文借助《几何画板》发现如果直角顶点为平面上任意一点时,一般地这些弦的包络仍然是一条圆锥曲线.下面对各 We know that the constant point on the conic curve at a fixed point over a certain point, this conclusion has been scattered in a variety of mathematical publications, such as [1], [2]. 2009 Beijing, Shandong college entrance examination paper analytic geometry But also involve the ellipse and hyperbolic the center of the rectangular rectangular chord problem.This inspired us to explore the general position of the conic curve on the plane of the fixed point rectangular rectangular string properties.We use the “geometric sketchpad” found that if the right-angled vertices for any plane At some point, the envelope of these strings is generally a conic curve