1 . 在正方体
中,M,N分别是线段
,
的中点,给出下面结论:
①
平面
;②
;③
平面
;④平面MNB与平面ABCD相交.
其中正确结论的序号为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66fb71b75b63594ebeeeebd1963eed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/394c5d2f55221975503be8aa18022480.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/02438f0423acd0ff2dfa5ffb6abf143f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e53b212640dadf751ef7f65a78a209.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f308dbf591d107899c6b6a294037088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93cf663ee2bf1ac5c43f4306fa0cf250.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2bf9ef324f1289e205e29fed105c38e.png)
其中正确结论的序号为
您最近一年使用:0次
2 . 根据下列条件能否判断直线与平面图形所在平面垂直:(能的写正确;不能的写错误)
(1)直线垂直于三角形的两条边.( )
(2)直线垂直于梯形的两条边.( )
(3)直线垂直于圆的两条直径.( )
(1)直线垂直于三角形的两条边.
(2)直线垂直于梯形的两条边.
(3)直线垂直于圆的两条直径.
您最近一年使用:0次
3 . 过
所在平面
外一点
作
,垂足为
,连接
.给出下面四种说法:
①若
,则点
是
的外心;
②若点
到
三边所在直线的距离都相等,则点
是
的内心或旁心;
③若
,则点
是
的垂心;
④若
与平面
所成的角都相等,则点
是
的外心.
其中所有正确说法的序号是__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59169f91ebc758ba6e73fc99fcfaab15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4116894d7b972f8d7b7a761820adcd84.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30fc65a72853bd8ac1ad0828270d3baf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
②若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
③若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/684265abf6458d2571adfa7d2f3db16c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
④若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4116894d7b972f8d7b7a761820adcd84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
其中所有正确说法的序号是
您最近一年使用:0次