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[几何] 求证

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student_qwh Posted 2017-12-1 19:42 |Read mode
191332bnanbn6d3bfz6ggb[1].gif

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 Author| student_qwh Posted 2017-12-1 19:43
别的地方看到的,到不是不会做,纯属分享,一起想想看

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乌贼 Posted 2017-12-2 02:11
Last edited by 乌贼 2017-12-2 02:26 211.png
不对,
令$ CV=1 $,取$ QB=5 $,如命题成立,应有\[MT//QD\]即\[ \angle MTK=\angle QDB \]但\[ \begin{align*}
&MK=IH=6\\&TK=\sqrt{MT^2-MK^2}=\sqrt{92}\\&\dfrac{MK}{TK}=\dfrac{6}{\sqrt{92}}\ne\dfrac{QB}{DB}=\dfrac{5}{8}
\end{align*}\]即\[  \angle MTK\ne\angle QDB \]

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kuing Posted 2017-12-2 04:19
所有东西都固定的,死算好了,建系计算最终得
\[\frac{NV}{NG}=\frac{3}{26}\bigl(2\sqrt{23}-1\bigr)\approx0.991345736,\]
的确很接近相等。

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 Author| student_qwh Posted 2017-12-2 12:16
谢谢回答

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