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[几何] 抛物线的点到圆的距离最值问题

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facebooker posted 2019-5-5 17:27 |Read mode
Last edited by facebooker 2019-5-5 17:54咋整啊 做一道题一道题都是坎啊。。。
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kuing posted 2019-5-5 19:24
没什么难的啊……
记圆心 `M(2,0)`,注意它也正好是抛物线的焦点,所以
\[\frac{PA^2}{PQ}\geqslant\frac{PA^2}{PM+MQ}=\frac{(x-3)^2+y^2}{x+2+1}=\frac{(x-3)^2+8x}{x+3}=x+3+\frac{12}{x+3}-4\geqslant4\sqrt3-4,\]取等略。

PS、建议用代码输入,尽量不贴图:一、便于日后搜索;二、节省空间。

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isee posted 2019-5-5 20:50
回复 2# kuing


估计楼主是纯新手,我估计需要你层主做个示范。。。实例。。。

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