1 . 如图,正方体
的棱长为
分别是棱
,
的中点,过点
的平面分别与棱
,
交于点
,设
.给出以下四个命题:
①平面
与平面
所成角的最大值为45°;
②四边形
的面积的最小值为
;
③四棱锥
的体积为
;
④点
到平面
的距离的最大值为
.
其中命题正确的序号为( )
![](https://img.xkw.com/dksih/QBM/2020/5/2/2453956736622592/2454806536454144/STEM/660af814c0024051a7b239dc45ea4ee0.png?resizew=197)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8facdca5180b1b029fbe71f549f557e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad056c25c0fdcbcc765eb5cbc6093f2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22adbc0da438220f9cace11b629d799b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c0f067a2a348ceb24a408f82992eab8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d19553a85c482a3c4c68f350101db356.png)
①平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1522a9c3b2466395570c2689a4055584.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
②四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1522a9c3b2466395570c2689a4055584.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8cc0b4997cae4d8aec791a1d3923314.png)
③四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11719e323e73b9512869d6aca6aaae75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ded50423a537949540817c34e1578d58.png)
④点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1522a9c3b2466395570c2689a4055584.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79e0a1e05c99b76ed068c1c479b5ff78.png)
其中命题正确的序号为( )
![](https://img.xkw.com/dksih/QBM/2020/5/2/2453956736622592/2454806536454144/STEM/660af814c0024051a7b239dc45ea4ee0.png?resizew=197)
A.②③④ | B.②③ | C.①②④ | D.③④ |
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