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[几何] PISA题

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lrh2006 Posted 2022-4-5 14:34 |Read mode
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kuing Posted 2022-4-5 17:22
印刷机质量太渣,图1都糊成啥样了……图2又被画过……这怎么做啊……

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 Author| lrh2006 Posted 2022-4-5 18:17
回复 2# kuing

水平和竖直的线是自己画的

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kuing Posted 2022-4-5 21:30
话说,“PISA 题”是啥意思

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 Author| lrh2006 Posted 2022-4-6 16:01
回复 4# kuing

中考PISA题大概是指注重应用与情景化的题目吧,国际上有PISA测试,我们可能是借用了这个名称

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kuing Posted 2022-4-6 16:05
哦,我第一反应是吃的匹萨……

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 Author| lrh2006 Posted 2022-4-6 16:20
回复 6# kuing


   
哈哈,我第一次听到也很奇怪,为啥叫披萨题呢,和披萨有啥关系呢,啊啊啊,我终于和偶像有一样的脑回路哈哈哈

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kuing Posted 2022-4-6 16:21
回复 7# lrh2006

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kuing Posted 2022-4-6 17:00
回复 9# hbghlyj

最后那个角是固定的 105°,因此正三角形时,MP 与水平线成 45° 夹角,这里就用到 `\sqrt2` 了

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kuing Posted 2022-4-6 17:24
正三角形时,设 `AB=x`,则 `AM=4\sqrt3x`, `MP=\frac12x`,如楼上所说,P 到 AB 的距离为 `AM+MP\cos45\du`,所以
\[4\sqrt3x+\frac{\sqrt2}4x=143,\]
代近似值发现恰好 `x=20`,这么整,可以肯定这就是命题者所想要的,然后
\[PQ=AB-2MP\sin45\du=x-\frac{\sqrt2}2x=20-10\sqrt2=6.\]

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