如图,在三棱锥
中,
,
,点
为
中点,
是
上一点,
底面
,
面
.
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/8b409250e8284a5b99560171eebe8698.png)
(1)求证:
为
中点;
(2)当
取何值时,
在平面
内的射影恰好是
的中点.
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/c29870433a19470293a67a7bab07feb0.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/eb7e37a162654bb681e7ac2c40659068.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/8497f833a51d4476b9511611643c4a03.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/703a66f358b640bfa6af53f70e8d11e5.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/026a735903f343abb14b76be22b259cd.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/44e39aa6328944b49bde881f0cb68af3.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/312a1c381f784ef3a3d9859171a4156b.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/54008c53b0ab4cba9be1bb06464c7e81.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/c71c4a530c7344e0b0fdb6af356e3fcf.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/6d29b9cee3754af69ec7bce10f1ae57c.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/52ae8e3d5c7845fdb76152fd3d3dc8c9.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/8b409250e8284a5b99560171eebe8698.png)
(1)求证:
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/44e39aa6328944b49bde881f0cb68af3.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/312a1c381f784ef3a3d9859171a4156b.png)
(2)当
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/854b331455bd481d89bc37ad7d6f1a84.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/703a66f358b640bfa6af53f70e8d11e5.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/6a86a48c8bed4f2894580529b3d1795d.png)
![](https://img.xkw.com/dksih/QBM/2017/2/8/1625057959280640/1625057959772160/STEM/33b39b962eea48c7b2c79ba0cddc64c8.png)
更新时间:2017-02-16 08:51:47
|
【知识点】 证明异面直线垂直
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解答题-问答题
|
较易
(0.85)
【推荐1】已知正方体AC1的棱长为a,过B1作B1E⊥BD1于点E,过点E作EF⊥BD于F.
![](https://img.xkw.com/dksih/QBM/2016/3/28/1572560383500288/1572560389644288/STEM/5dbfaec74dc246d6b2170aef5e0d4870.png)
(1)证明EF∥平面ABB1A1;
(2)求A,E两点之间的距离.
![](https://img.xkw.com/dksih/QBM/2016/3/28/1572560383500288/1572560389644288/STEM/5dbfaec74dc246d6b2170aef5e0d4870.png)
(1)证明EF∥平面ABB1A1;
(2)求A,E两点之间的距离.
您最近一年使用:0次
解答题-证明题
|
较易
(0.85)
【推荐2】如图,在四棱锥
中,
为正三角形,
⊥平面
,
⊥平面
,
为棱
的中点,
.
![](https://img.xkw.com/dksih/QBM/2015/6/25/1572145638940672/1572145644634112/STEM/5335e79d0caa48d5bb236c156d3b03c6.png)
(I)求证:
平面
;
(II)求证:平面
⊥平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8e7cedc39297d66dbb177f2a1f6bee2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fc56c77464a17a1e97b568762a3e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1642eec556eb252de9c1ab7bb5ca90b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/941eb121a0a82776bcf11768960c66c3.png)
![](https://img.xkw.com/dksih/QBM/2015/6/25/1572145638940672/1572145644634112/STEM/5335e79d0caa48d5bb236c156d3b03c6.png)
(I)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f9fbdf06226a2365e120a88ea22e067.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(II)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bc46688d8723cf2003fc25890265200.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0c08e455f522d580b10dbf547949682.png)
您最近一年使用:0次