9-10高二下·四川眉山·期末
解题方法
1 . 将边长为2,锐角为
的菱形
沿较短对角线
折成二面角
,点
分别为
的中点,给出下列四个命题:
①
;②
是异面直线
与
的公垂线;③当二面角
是直二面角时,
与
间的距离为
;④
垂直于截面
.
其中正确的是______________ (将正确命题的序号全填上).
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/4f3bdc47383c4188a1d0cd702232287b.png?resizew=27)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/d5011570b2af442ca2d6a16aa50b4819.png?resizew=48)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/ca65a43e3494478a95118b55346ce9a6.png?resizew=27)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/810255ef761d4c66a79254944bbfd535.png?resizew=79)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/f74b0e92ecab4e3e9f7c16e34c55b10e.png?resizew=33)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/ec89d7d6c115471c900a65d2925c77ae.png?resizew=56)
①
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/83d1761e17144cd5bfa0cea20333825a.png?resizew=61)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/89fa0ce58e95410cae81a945bb88bbd8.png?resizew=27)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/ee62b038fee34cc08497b0e126e9f4fe.png?resizew=28)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/ca65a43e3494478a95118b55346ce9a6.png?resizew=27)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/810255ef761d4c66a79254944bbfd535.png?resizew=79)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/ee62b038fee34cc08497b0e126e9f4fe.png?resizew=28)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/ca65a43e3494478a95118b55346ce9a6.png?resizew=27)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/6491e1a091b04eb48433ba3bdcad725d.png?resizew=28)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/ee62b038fee34cc08497b0e126e9f4fe.png?resizew=28)
![](https://img.xkw.com/dksih/QBM/2014/7/7/1571812019953664/1571812025393152/STEM/170241cf8bdd4d57a06b594c39ce0453.png?resizew=37)
其中正确的是
您最近一年使用:0次
2012·四川内江·二模
解题方法
2 . 如图,设平面α∩β=EF,AB⊥α,CD⊥α,垂足分别为B,D,若增加一个条件,就能推出BD⊥EF,现有:
①AC⊥β;
②AC与α,β所成的角相等;
③AC与CD在β内的射影在同一条直线上;
④AC∥EF,
那么上述几个条件中能成为增加的条件的序号是_____ (填上你认为正确的所有序号)
①AC⊥β;
②AC与α,β所成的角相等;
③AC与CD在β内的射影在同一条直线上;
④AC∥EF,
那么上述几个条件中能成为增加的条件的序号是
![](https://img.xkw.com/dksih/QBM/2012/4/12/1570834352365568/null/STEM/51f6075608a1456fa38f8b0112fecef5.png?resizew=163)
您最近一年使用:0次
10-11高三·四川成都·阶段练习
3 . 已知在三棱锥T-ABC中,TA,TB,TC两两垂直,T在底面ABC上的投影为D,给出下列命题:
①TA⊥BC, TB⊥AC, TC⊥AB;
②△ABC是锐角三角形;
③
;
④
(注:
表示△ABC的面积)
其中正确的是_______(写出所有正确命题的编号).
①TA⊥BC, TB⊥AC, TC⊥AB;
②△ABC是锐角三角形;
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b512bffd8105d43e3531eb2a08d4646a.png)
④
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dac445e253feed6749f0cdb722eb7372.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5cbff84327e964f912a54032e76ccc9.png)
其中正确的是_______(写出所有正确命题的编号).
您最近一年使用:0次