1 . 如图,正方体
的棱长为1,
分别为
的中点,过直线
的平面分别与棱
交于点
.设
,给出以下四个结论:
![](https://img.xkw.com/dksih/QBM/2020/7/10/2503000483315712/2503858342428673/STEM/cd1609fd1e5343b39da958d419aa65d7.png?resizew=198)
①平面
平面
;
②当且仅当
时,四边形
的面积最小;
③四边形
的周长
是单调函数;
④四棱锥
的体积是定值.
其中正确结论的序号为______ (请写出所有正确结论的序号).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad056c25c0fdcbcc765eb5cbc6093f2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8e86e3991200297ad172455e5ea93f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31be3b7305d6c181420ea7b28c420851.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d87dccaf9f65ef67b126e9cf94bd8694.png)
![](https://img.xkw.com/dksih/QBM/2020/7/10/2503000483315712/2503858342428673/STEM/cd1609fd1e5343b39da958d419aa65d7.png?resizew=198)
①平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c1f56858867e7b6becaeac49112a3d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2bf9ef324f1289e205e29fed105c38e.png)
②当且仅当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b650820d7bed48ed67a2869ad8c65ff1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65e92eac740953aa383be636ea90fd47.png)
③四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65e92eac740953aa383be636ea90fd47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a1d36150a026bbd7a16b8bc936e214.png)
④四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1cb21d0d3f430f009b677eb8945323e1.png)
其中正确结论的序号为
您最近一年使用:0次
2 . 对于函数
,若存在区间
,
,使得
,
,则称函数
为“同域函数”,区间
为函数
的一个“同城区间”.给出下列四个函数:
;②
;③
;④
.
存在“同域区间”的“同域函数”的序号是__________ .(请写出所有正确结论的序号)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de992c982935cef2002b2c8104c00ad3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b0b703034e508086831b5008a22939b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5cb3641952a71fc4fcd82c5fb7e58b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ffb73da207dea41fff108ae750e43ab8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c6a3695649d3c9ead7a7233557e3b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/267e6d77aabbebe52e7aca993368d874.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f294ed9d641d73656256d524359d3d42.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2c7082ad32db40f04008553b1d366b9.png)
存在“同域区间”的“同域函数”的序号是
您最近一年使用:0次