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最近笔者在讲授《几何证明选讲》(普通高中课程标准实验教科书数学选修4-1,人教A版,以下简称课本)时,也发现了一种过椭圆(双曲线)上任意一点作切线的新方法,这种方法比文[1]、文[2]介绍的方法还要简便,现整理如下,仅供参考.课本第32页习题2.3第3题是:如图1,AB是⊙O的直径,BC是⊙O切线,切点为B,OC平行于弦AD,求证:DC是⊙O的切线.
Recently, I also found an oval (hyperbolic) at any point on the tangential (hyperbolic curve) when teaching “Geometry Proof” (the standard high school curriculum standard textbook mathematics elective 4-1, A teach A version, hereinafter referred to as the textbook) , This method than the text [1], text [2] to introduce the method is also simple, is now organized as follows, for reference only. Page 32 Exercises 2.3 The third question is: Figure 1, AB is ⊙ O diameter, BC is ⊙ O tangent, tangent point B, OC parallel to the string AD, verify: DC is ⊙ O tangent.