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[几何] 已知圆锥曲线上五点或圆锥曲线上五切线作圆锥曲线

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hejoseph Posted 2016-2-16 14:13 |Read mode
这里主要是要得到确定轴、焦点的方法,有了这些量,圆锥曲线看作已经能作图了
$type 圆锥曲线.pdf (120.77 KB, Downloads: 4644)

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 Author| hejoseph Posted 2019-3-26 09:20
现在可以通过任意五元素(点或切线)的组合作出圆锥曲线的主要量,并且有这五个元素就可以简单地作出与直线的交点和过定点的切线
$type 已知圆锥曲线上五元素(点或切线)作圆锥曲线.pdf (157.68 KB, Downloads: 7105)

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 Author| hejoseph Posted 2023-4-26 15:32
Last edited by hejoseph 2023-4-26 16:13在原来的文档里添加了一些作图方法
$type 圆锥曲线的几何作图法.pdf (205.27 KB, Downloads: 66)

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hbghlyj Posted 2024-3-27 08:08
抛物线 维基有一个GIF图:
File:Parabola construction given five points.gif
Parabola_construction_given_five_points.gif Two parabolas, intersecting in four points may be distinct. But if they intersect in five points, then they coincide, so a parabola, like ellipse and hyperbola, is defined by five points. Here, we construct parabola, given five points. For the description of the method see p. 83 of the following book: A.P. Veselov, E.V.Troitsky. Lectures in Analytical Geometry. 2nd ed., in Russian. Lan', 2003. See also a description and an applet for the ellipse here.

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