1 . 在三棱锥
中,
,
分别为棱
的中点.现有以下4个结论:
①三棱锥
的外接球表面积为
;
②
;
③
平面
;
④当
时,平面
平面
.
则其中正确结论的序号为______________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e561abd2bb54ac40d4f7af31ff9f7397.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e96c92bc20565fb976e0c73ee4017261.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ceeb10380ea1162ae9078c9b93adb846.png)
①三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4a39dce3f1e36dbe01293c309816968.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44b0e8d6874ca0163575176a49accf45.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d07d16fc91aa960b67ba4b474de8a62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/05a270ec7e23fc0cc1d4b04bf1d22184.png)
④当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3755b2bcf7516eedb26a27ad73657216.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4aa9084b8fe0fe05c4388d1f835587b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
则其中正确结论的序号为
您最近一年使用:0次
解题方法
2 . 已知正方体
,过对角线
作平面
交棱
于点
,交棱
于点
,则:
①平面
分正方体所得两部分的体积相等;
②四边形
一定是平行四边形;
③平面
与平面
不可能垂直;
④四边形
的面积有最大值.
其中所有正确结论的序号为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe734023d4e70010a6b2cc3267cb86e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
①平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
②四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ef5ea43614d815c3abb27a42dfb101b.png)
③平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1477ae90a240deba97f8dadf4d7c41aa.png)
④四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ef5ea43614d815c3abb27a42dfb101b.png)
其中所有正确结论的序号为( )
A.① | B.② | C.③ | D.④ |
您最近一年使用:0次