如图,已知直三棱柱
中,D,E,F分别为AC,
,
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/31/8ab0e165-a831-4131-a12c-7353ba064d71.png?resizew=158)
(1)求证:
平面ABC;
(2)若△ABC为等腰直角三角形,∠ABC=90°,且
.求证:
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/31/8ab0e165-a831-4131-a12c-7353ba064d71.png?resizew=158)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7a407b262c22419f73396170ecdc849.png)
(2)若△ABC为等腰直角三角形,∠ABC=90°,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d289a52b00154f78031af90afa02135.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047da2786ecd6c3b0248908e72593c66.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bf9628142422a4884bd59538da6d312.png)
更新时间:2022-07-03 00:12:45
|
相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图所示,在三棱柱
中,侧棱
底面
为
的中点.
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/10/a3d3f6e2-ff05-4b08-be7c-47a328dada40.png?resizew=140)
(1)证明:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a67bf895a23201ad71b4e21894bb530c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5f5248a3386e69422ace11562ae30cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5751a64f204698a16ecdf339da16e53.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/10/a3d3f6e2-ff05-4b08-be7c-47a328dada40.png?resizew=140)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/638537c0a30676c73fea76c80e0f8bd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a935b7d21a103a264b6e96ecf82dbe4a.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd190b5a26dfb45a06c1d6ee86dd82d9.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
【推荐2】如图,在直三棱柱
中,
,
,D是BC的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/6/047e9828-1de1-4af6-a12d-0efb6bfccd55.png?resizew=180)
(1)求证:
平面
;
2).求二面角
的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80969d2b85b57d776a482dde2df0f5a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc555c17a209c7d5cae35bb11b8830e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5af99bbb02d22f3f582584092ad1beb0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/6/047e9828-1de1-4af6-a12d-0efb6bfccd55.png?resizew=180)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47f5233985626c2701be0394ebc1ecfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/803bcb6a4465ad0d433651156f7337cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11d71379442f28c038d367d49422cf90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f25c5543b39190dc2499aa66f939659.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
【推荐1】如图,在四棱锥
中,底面
为菱形,
,点
为
的中点,
且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/16/fa430242-1c21-4258-8796-e50332819bb3.png?resizew=194)
(1)求证:
平面
;
(2)若
,求平面
与平面
所成二面角的余弦值;
(3)在第(2)问的前提下,求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71a46dc0bb5d8fa33583817e530a5d21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e18a77f741b7f3553a7fa83e653ac667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/854f4df35b7d57bf69dea9f6cafa8fae.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/16/fa430242-1c21-4258-8796-e50332819bb3.png?resizew=194)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/898f8f0c4060848800eb8df8ebb876fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdfa54114f04a75b8c96165b3718ed7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(3)在第(2)问的前提下,求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐2】已知三棱锥
(如图一)及其展开图(如图二),四边形ABCD为边长等于
的正方形,
和
均为正三角形.
![](https://img.xkw.com/dksih/QBM/2022/1/14/2894173616365568/2895610469597184/STEM/9d2addbb-50c7-4805-b1ce-311bc2c73339.png?resizew=330)
(1)证明:平面
平面ABC;
(2)若点M在棱PA上运动,当直线BM与平面PAC所成的角最大时,求点M到平面PBC的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e742966e3711cfa53dce04022acf4bcc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6830ebecddbd9759be626289c408e4f3.png)
![](https://img.xkw.com/dksih/QBM/2022/1/14/2894173616365568/2895610469597184/STEM/9d2addbb-50c7-4805-b1ce-311bc2c73339.png?resizew=330)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d077f6da8b2c00b152d4679aa2ed7f7.png)
(2)若点M在棱PA上运动,当直线BM与平面PAC所成的角最大时,求点M到平面PBC的距离.
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