如图,在三棱锥
中,
,D、E分别是AB、AC的中点,且
平面ABC.
![](https://img.xkw.com/dksih/QBM/2020/3/12/2418141298819072/2432991658786816/STEM/3eec0a29c1374b0bb538621cd7a01891.png?resizew=284)
(1)求证:
平面PDE;
(2)求证:
平面PDE.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db807b09cc550f476b3f8fa0c6a14425.png)
![](https://img.xkw.com/dksih/QBM/2020/3/12/2418141298819072/2432991658786816/STEM/3eec0a29c1374b0bb538621cd7a01891.png?resizew=284)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/963a91995abd4927d75406d16e10a81f.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f9157fce2a8339d281178c7c0bccbe.png)
更新时间:2020-04-02 20:37:06
|
相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图,四边形ABCD为正方形,四边形BDEF为矩形,AB=2BF,
平面ABCD,G为EF中点.
![](https://img.xkw.com/dksih/QBM/2011/4/6/1570104389771264/1570104394997760/STEM/953ee4c99ea943979bd9258c41034170.png?resizew=189)
(1)求证:
平面
;
(2)求证:平面
丄平面
;
(3)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7a38e6c6dfde2b19b6b47f35a439a06.png)
![](https://img.xkw.com/dksih/QBM/2011/4/6/1570104389771264/1570104394997760/STEM/953ee4c99ea943979bd9258c41034170.png?resizew=189)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94270844f197d524bf1da4f1385befd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9a32bd7a1b78b5a0ec562c4025aea8c.png)
(2)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90131175c3fb6a3837a22d7d5bbc268d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af841bc357e88fac4834ea8b6b3e9207.png)
(3)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcf30f4076f9d389add8939311004303.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
【推荐2】在正方体
中,S是
的中点,E,F,G分别是BC,DC,SC的中点,求证:
![](https://img.xkw.com/dksih/QBM/2022/4/26/2966366442954752/2970542550188032/STEM/0f39c8cf-88f6-48e3-93ba-ea1966b616d4.png?resizew=180)
(1)
平面
;
(2)平面
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cfbc0b5a8fbde804bd8425a4b76d207.png)
![](https://img.xkw.com/dksih/QBM/2022/4/26/2966366442954752/2970542550188032/STEM/0f39c8cf-88f6-48e3-93ba-ea1966b616d4.png?resizew=180)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1399e7ae0b2decaafc62a5cdffb15522.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fefd8229243bcbee5ac197740e6c66ab.png)
(2)平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b3f73a75aa7d3e8926dea3513fa90f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/882bc11eba4f28780fc0d928ead2dbbc.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
名校
【推荐1】如图,平行四边形
中,
,
,
,沿
将
折起,且
在平面
上的射影为
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/d76fcb3e-727d-4af3-b698-20cde57a9dd4.png?resizew=505)
(1)求三棱锥
的体积最大值.
(2)当
时,求锐二面角
大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8915e8e775538d41debf1933102c6b86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d6bdfb0e1be5583e794ab614a8abe1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/661ff55b5ebbadfb600989af3cfce2fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/d76fcb3e-727d-4af3-b698-20cde57a9dd4.png?resizew=505)
(1)求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb01ad3508483c8929d5bf3fb8d5fc2c.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f1854ba6cc92481d7a616bd2788a47e.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐2】如图,四面体
中,
,
,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/6/8f33a6c4-db7e-4813-aa56-8c4e8300f91e.png?resizew=248)
(1)证明:
平面
;
(2)设
,
,
,点
在
上,当
的面积最小时,求
与平面
所成的角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdb2dd10731b99c0f4f89ee957f8a239.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd95dc30c0344788b94289c464a3158e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2aca1bdb9459855415e292e73de50ae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/6/8f33a6c4-db7e-4813-aa56-8c4e8300f91e.png?resizew=248)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e56fdf217165748fafe938b64fa08179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34be4e71cabf458f17a6cd7f24bc70af.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5322a78b02c2bc387ea7dce3e9461974.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82773737609e65dea3c5c67099f1b10d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/26fdd8e57562ba94e10e7f1d770826d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36691f0269294ecae8f00b7bce97756c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
解题方法
【推荐3】如图,在四棱柱
中,底面
为正方形,侧棱
底面
,
为棱
的中点,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/16/d6e58281-4ca1-4951-b80a-801590ee3268.png?resizew=144)
(1)求证:
平面
;
(2)求证:
平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ccc0d735dc14c92a8926d9b1def6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8d927585a17c2e98ef7d5a9589a26ac.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/16/d6e58281-4ca1-4951-b80a-801590ee3268.png?resizew=144)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07391ef575d28f09bc5cda0ff8130a54.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34be4e71cabf458f17a6cd7f24bc70af.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a5928c98b341b16d4b5a5b931d2929d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cc1c04946340198af69170d4ebd4b42.png)
您最近一年使用:0次