解题方法
1 . 如图,正方体
的棱长为1,线段
上有两个动点
,
,且
,现有如下四个结论:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/ed5cbbd6-708b-4639-b546-1de98f09e148.png?resizew=181)
①延长线段
和
必相交于一点;
②
;
③平面
平面
;
④三棱锥
的体积为定值.
其中正确结论的序号是___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cfbc0b5a8fbde804bd8425a4b76d207.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1461d297be1c046856b662e84553aaa.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/ed5cbbd6-708b-4639-b546-1de98f09e148.png?resizew=181)
①延长线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/589ddae20626f9aaac616d2a3b5d95bd.png)
③平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b0656936257a9fad7efc2f41b57322a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
④三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccc3bf74119692ac98eb24fcfa2a3f9f.png)
其中正确结论的序号是
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