1 . 已知四面体
的所有棱长均为
,M,N分别为棱
的中点,F为棱
上异于A,B的动点.有下列结论:
①线段
的长度为1;
②当F为棱
中点时,点C到面
的距离为
;
③
周长的最小值为
;
④三棱锥
的体积为定值.
其中正确结论的序号为_____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d93949d8a15aca4e79cedb978590571.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
①线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
②当F为棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/412ef8edcf697ce9606cf82f58d695f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecfb02e157819a2bdd0f2790cbc825e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d3f30e758b1fb5d2d9460507ea3616f.png)
④三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/103db3ac4bdebec8802988368ab11192.png)
其中正确结论的序号为
您最近一年使用:0次
2 . 如图,在棱长为
的正方体
中,
是侧面
内的一个动点(不包含四边形
的边),则下列错误 说法的序号是__________ .
![](https://img.xkw.com/dksih/QBM/2022/4/29/2968697326526464/2973001867108352/STEM/7bb6ac83-c81d-4eb7-ba45-eff3d6dc8484.png?resizew=145)
①三角形
的面积为
;
②存在点
,满足
;
③存在无限个点
,使得三角形
是等腰三角形;
④三棱锥
的体积有最大值、无最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
![](https://img.xkw.com/dksih/QBM/2022/4/29/2968697326526464/2973001867108352/STEM/7bb6ac83-c81d-4eb7-ba45-eff3d6dc8484.png?resizew=145)
①三角形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7850e88507969a07a9515347b97c7b6e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95bacae35b6e16a0a33c2bdc6bc07df7.png)
②存在点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a87e8258e0f105cbad09162b480e3ea5.png)
③存在无限个点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7850e88507969a07a9515347b97c7b6e.png)
④三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/926f0aafa25355ba0c5335dc538f4751.png)
您最近一年使用:0次