名校
解题方法
1 . 如图,正方体
的棱长为1,E,F分别是棱
,
的中点,过直线
的平面分别与棱
,
交于点M,N,设
,给出下列三个结论:①四边形
一定为菱形;②若四边形
的面积为
,
,则
有最大值;③若四棱锥
的体积为
,
,则
为常值函数.其中正确结论有多少个?( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/12/b30ed541-c8ff-4869-8fc7-c7fbd28c1b3b.png?resizew=161)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3da8c338342e38c9aa3f274c053fd5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6024fd4532f5f981deac4582c799a6ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20ecac2dad4cffdd971fd23deacff3fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6655cc150ddc9deba2254780984d0024.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82b25f3ea33cc08b1e2a0d9c3a9dccaf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91f2a9b923a355694ea487f6c5669a04.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65e92eac740953aa383be636ea90fd47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65e92eac740953aa383be636ea90fd47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f56fa5f9c9f324859bde42ee3ca620db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c7b69e93488fcd2a195cb9793e94fc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b941daa059b04aab552429ae22a1661d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3916aacf0509ae7ad573aa3b1dc34ac2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12a5f485aa5bcff83de6a238f7c8f712.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4669810732b633b60dbeaf0bf57204f6.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/12/b30ed541-c8ff-4869-8fc7-c7fbd28c1b3b.png?resizew=161)
A.0 | B.1 | C.2 | D.3 |
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