.如图所示,平面
平面
,点
,点
,点
,点
,点E,F分别在线段
,
上,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/27/d6a14c0e-5f54-4b47-a1b9-bb8c5c048efa.png?resizew=212)
(1)求证:
平面
;
(2)若E,F分别是
,
的中点,
,
,且
,
所成的角为60°,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/414844edd458857bdfc80bffa61cbf9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb0b6de90bb936cdb09629123100145d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4cc2f3dcb248fc764614be3a9ddd25b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16acea101c98a280a70c2fa0b2c04dd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eaccf1887c4b530fd86a2f0f199c6797.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b8e9d555eab6c0e597be56f8125f1d1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/27/d6a14c0e-5f54-4b47-a1b9-bb8c5c048efa.png?resizew=212)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57f9d682e5d3cc8573574d8d11636758.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
(2)若E,F分别是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8a7b5adfcac0f46a4cd19da4ebb4a2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/454328a8e75953fdb0835ce80d9566e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
更新时间:2020-10-23 16:04:27
|
相似题推荐
解答题-问答题
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适中
(0.65)
【推荐1】在
中,
,
,
分别为内角
,
,
的对边,已知
.
(1)求
.
(2)若
的周长为
,面积为
,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb0e6bc5f98fbd25b5fb1f2e0e463cf.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab46ea0cba2d06283fae3d864a2329e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/802e162b98c280720fcb909cf392fda3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
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(0.65)
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【推荐2】
的内角
所对的边分别为
,且满足
.
(Ⅰ)求
的值;
(Ⅱ)若
外接圆半径为
,求
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/237434d9b3e7fcaa7a56c5ab317cc935.png)
(Ⅰ)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5201fc26d013f6fb889933c0e32f5c53.png)
(Ⅱ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfdea2fcb0d447129c74900436dae014.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.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1】如图,三棱柱
中,
是底面边长为2的正三棱锥.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/2/beb0f4b5-86ce-4fac-9560-8b458b70fa85.png?resizew=169)
(1)求证:
;
(2)若异面直线
与
所成的角为
,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1157a6da4c4028b7216f7c9740d63aee.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/2/beb0f4b5-86ce-4fac-9560-8b458b70fa85.png?resizew=169)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a91b02ae9df63950c2b4152fd1edc091.png)
(2)若异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d88591679796c52024d11c4de641bdb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44dc7e4469c1fc443464c105b20f1224.png)
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解答题-问答题
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适中
(0.65)
【推荐2】如图(1)在等腰
中,
分别是
边的中点,
,现将
沿
翻折成直二面角
.(如图(2))
![](https://img.xkw.com/dksih/QBM/2012/3/26/1570821008924672/1570821014478848/STEM/5ed8240f33af47dfad671e71643b6fc4.png?resizew=107)
![](https://img.xkw.com/dksih/QBM/2012/3/26/1570821008924672/1570821014478848/STEM/8658f617d6bd4cf89247a399f9b7db28.png?resizew=154)
(I)试判断直线
与平面
的位置关系,并说明理由;
(II)求二面角
的余弦值;
(III)在线段
是否存在一点
,但
?证明你的结论.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/927456b0989846a2f1573844bbaa2105.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942e6dafcfcbf0682856b9f25178694d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a1be17e0a3e51cde1f50f384198e71e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6dfb039aafe2d2841f8c28b117cf741.png)
![](https://img.xkw.com/dksih/QBM/2012/3/26/1570821008924672/1570821014478848/STEM/5ed8240f33af47dfad671e71643b6fc4.png?resizew=107)
![](https://img.xkw.com/dksih/QBM/2012/3/26/1570821008924672/1570821014478848/STEM/8658f617d6bd4cf89247a399f9b7db28.png?resizew=154)
(I)试判断直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
(II)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e685dde92d0192739da59f6e43b808e3.png)
(III)在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e32cf73c01995c91c3523fa11b3bd7d.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1】如图,
中,
,
是边长为1的正方形,平面
底面
,若
,
分别是
,
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/12/0ac22f9f-90f1-454b-a741-d4e0db69deb8.png?resizew=160)
(1)求证:
平面
;
(2)求证:
平面
;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6321a96e7f0768394f6932a121adc84e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1d70676406f26d339465fe3473c0c05.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5352d28609d1b3d09a0a29d023d1bb72.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fc56c77464a17a1e97b568762a3e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/12/0ac22f9f-90f1-454b-a741-d4e0db69deb8.png?resizew=160)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf60ad9db3411f35704fa88d86bfef5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d78fc7fcb2762de28dcef8aa3aa0e49.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36148e5b0d89ba45bd98b91da00bf2b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8257b6bd25104e07b9ad935c0a3aac4.png)
您最近一年使用:0次
解答题-证明题
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适中
(0.65)
名校
解题方法
【推荐2】在△ABC中,AB
4,
,∠BAC=45°,以AC的中线BD为折痕,将△ABD沿BD折起,构成二面角A-BD-C,在平面BCD内作CE⊥CD,且
,连接DE,AE,AC,如图所示.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/25/a84ddae9-a077-48d3-878b-0414faa00916.png?resizew=153)
(1)求证;CE//平面ABD;
(2)若二面角A-BD-C的大小为90°,求二面角B-AC-E的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac8857e7eccc1693fe32a8db9debfda6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f19db51e651e7f5275ec6ee393cc94e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0f281cde68437cf00c3f3fbbccf9340.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/25/a84ddae9-a077-48d3-878b-0414faa00916.png?resizew=153)
(1)求证;CE//平面ABD;
(2)若二面角A-BD-C的大小为90°,求二面角B-AC-E的余弦值.
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