如图,三棱锥
中,
是正三角形,
平面
,
,
为
中点,
,垂足为
.
![](https://img.xkw.com/dksih/QBM/2016/4/6/1572566745825280/1572566752026624/STEM/421e609026924f248f19cf77e5427b36.png?resizew=208)
(1)求证:
;
(2)求二面角
的平面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5f1897a7e856b42f8cee0f286ad913d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c2c9c32921b9f678056406dbb27fd9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b53d1e3701b45f028de14ae8166c75c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/2016/4/6/1572566745825280/1572566752026624/STEM/421e609026924f248f19cf77e5427b36.png?resizew=208)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ae20968d87623467882df2b5c2ceab1.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed7a8116d2f02b52c33fb7a49fc0d1ae.png)
更新时间:2016-12-04 04:58:09
|
相似题推荐
解答题-证明题
|
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(0.85)
【推荐1】如图,已知
平面
,平面
平面
,
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/30/9eeedbf7-2480-41c9-845e-4615fcb99158.png?resizew=156)
(1)求证:
;
(2)若
,求异面直线
与
所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5dd496ee0c1170ef6dcc48266ee444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/905e950cc8fc6f92f31c62c784cbbc26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/780d3f5f4c4419913c1232b7aae03ade.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/30/9eeedbf7-2480-41c9-845e-4615fcb99158.png?resizew=156)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8af620f6d204d310d8e3f267fdd6c3f8.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0768c5313afe6a0824c041a0ea6cf9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d97dc3b752832906de41447bb58a341.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
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解答题-问答题
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解题方法
【推荐2】如图,三棱柱
中,侧面
底面
,
,
.
![](https://img.xkw.com/dksih/QBM/2021/3/11/2675807646539776/2684086746284032/STEM/f2f6e561d9bc4f8a87b0b5650c92a6b3.png?resizew=165)
(1)证明:
;
(2)若
与平面
所成角的正弦值为
,求四面体
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61cdaadeae37736a1e6dd93fa1fe712f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e96a6b20a35af7755e5d90789ea862da.png)
![](https://img.xkw.com/dksih/QBM/2021/3/11/2675807646539776/2684086746284032/STEM/f2f6e561d9bc4f8a87b0b5650c92a6b3.png?resizew=165)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47af45fbf1714055d9b414a44a8613fa.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07b7903de4be7d5dc1175cfbf6e8da9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/821309f088a175c00dc0f4828334503d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43a324dac874c952bfe21d6ec6eeb231.png)
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名校
【推荐3】已知几何体ABCDEF中,平面ABCD⊥平面CDEF,四边形ABCD是边长为4的菱形.∠BCD=60°,四边形CDEF是直角梯形,EF
CD,ED⊥CD,且EF=ED=2.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/14/e0e5b362-c142-4076-80f9-e92eba3c304f.png?resizew=175)
(1)求证:AC⊥BE:
(2)求平面ADE与平面BCF所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/638537c0a30676c73fea76c80e0f8bd0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/14/e0e5b362-c142-4076-80f9-e92eba3c304f.png?resizew=175)
(1)求证:AC⊥BE:
(2)求平面ADE与平面BCF所成角的余弦值.
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解答题-问答题
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名校
【推荐1】如图,在四棱柱
中,底面ABCD是一个平行四边形,
是边长为2的正三角形,E为
的中点,F为AB的中点,侧棱
平面
,
.
![](https://img.xkw.com/dksih/QBM/2021/12/17/2874353918009344/2879303316905984/STEM/f96ef099-2ef2-406c-8cb3-54d4f20f81ca.png?resizew=209)
(1)证明:
平面
.
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22adbc0da438220f9cace11b629d799b.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/92535536bd3c2761724fd058427f95a8.png)
![](https://img.xkw.com/dksih/QBM/2021/12/17/2874353918009344/2879303316905984/STEM/f96ef099-2ef2-406c-8cb3-54d4f20f81ca.png?resizew=209)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7a407b262c22419f73396170ecdc849.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96872cd6cd581ae8a861c7032e0257b4.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96e59022b89a622372ab7716bd206f35.png)
您最近一年使用:0次
解答题-证明题
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(0.85)
解题方法
【推荐2】如图,在正三棱柱
中,
为侧棱
的中点.
平面
.
(2)若
,求平面
与平面
所成二面角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0532c912a8b7953d35c6aac416478325.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d9a8181f7a7fe7f3fac872ce9534f15.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b4afa61e0bcb124aec52ad0cc84fd94.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f233b375753611ffa7a93c2c12ef5e28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99b16cff607cdc2d69afc70dc778acbb.png)
您最近一年使用:0次