1 . 如图,在正方体
中,
为线段
上的动点,则( )
![](https://img.xkw.com/dksih/QBM/2021/2/3/2650250947133440/2651642747568128/STEM/a7051e281a584657b416f02f49e121de.png?resizew=302)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93ecad355286188fd317939fa50f9555.png)
![](https://img.xkw.com/dksih/QBM/2021/2/3/2650250947133440/2651642747568128/STEM/a7051e281a584657b416f02f49e121de.png?resizew=302)
A.![]() |
B.三棱锥![]() ![]() |
C.异面直线![]() ![]() ![]() |
D.直线![]() ![]() ![]() |
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解题方法
2 . 已知
是不同的直线,
是不重合的平面,给出下列命题:
①若
,则
与平面
内的无数条直线平行 ②若
则
③若
,则
④若
则
上面命题中,真命题的序号是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/280860dd039e1305a5ccc455f63e8223.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4e288596fa3811dd2c17bded60e82e7.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6a4c549e7ea8776ec821c467bc1a913.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a0609cfeb92293dd3644c51ec35e8fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80645381feb9746cc149da61d553974a.png)
③若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c11cb27689ee14f6c14920e0f524175e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/384a65ca1ee3d7d86b988ca34c885e18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5875f4c63d7c3b16a95ae70f6ad1f810.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc01d7aa51bf4f95c4b12ae9dcb7eb4c.png)
上面命题中,真命题的序号是( )
A.①③ | B.①④ | C.②④ | D.①③④ |
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