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[几何] 圆中证线段和差关系

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isee Posted 2018-6-27 19:35 |Read mode
如图,圆中两条弦$AB>BC$,点$D$为弧$ABC$的中点.
(1)若点$D$在弦$AB$上的射影为$E$,探究$AE$,$EB$,$BC$这三条段段之间的数量关系;
(2)探究$AB\cdot BC$与$DA$,$DB$之间的数量关系.
circle-pt.png

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kuing Posted 2018-6-28 01:16
前不久才见过(第一问),好像还有名称,想不起来了,应该已经是被撸烂了的

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 Author| isee Posted 2018-6-28 10:23
回复 2# kuing

深圳2018年中考数学选了这个

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kuing Posted 2018-6-28 14:32
想起来了,阿基米德折弦定理:baike.baidu.com/item/阿基米德折弦定理/10738376

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lemondian Posted 2018-6-28 15:12
回复 3# isee

这个是深圳中考的原题吗?

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 Author| isee Posted 2018-6-28 15:15
回复 5# lemondian

不是。原题是证,不是究。且没主楼的(2)但还有别的问。

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lemondian Posted 2018-6-28 15:24
回复 6# isee
QQ截图20180628152214.jpg
是这个题不?我在网上找了一下,好多说是深圳2018中考题,很多套都不一样

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kuing Posted 2018-6-28 15:33
你们竟然撸完高考还撸中考……

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 Author| isee Posted 2018-6-28 15:34
回复 7# lemondian

是的,虽然题的表述欠完整,但意思是对的。


回复 8# kuing


看下命题动向,热点。

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