如图,在三棱柱
中,
平面
,
,
.
(1)求
与平面
所成的角;
(2)若
,求四棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2ffc6952e988d04f22f0fb2f7f0ab7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ac61c24f99a4e466f1e2ea011893866.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6772dad8331d44f5ac1f9de571ee85b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6de3e3f45e33000f06d42edc0a6dbbdd.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/5/b81279f8-7da7-46ac-a9c4-4cf691e575b5.png?resizew=147)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a696a182fff038a86b2bbe8ca099442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c44a10a595a695b1d07658b2bf1cc4a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c61e6d34503a713684bb25be96edbcd.png)
更新时间:2023-09-05 16:01:23
|
相似题推荐
解答题-证明题
|
适中
(0.65)
名校
【推荐1】如图,
是平行四边形,
平面
,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/3/b16b2259-2bb0-41ff-9909-065035077d69.png?resizew=134)
(1)求证:
平面
;
(2)求四面体
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f95475bfc06e884754eb4a455c3f434e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23a146d4e886817fdeecba419b3692e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9b5d2943803894bc5d204e75e2d172b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f04edd173055da613832b187737ce4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d31430a87a688a727b86e4001dcb3e6.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/3/b16b2259-2bb0-41ff-9909-065035077d69.png?resizew=134)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/871221c3eaabb6d9b030ce91c7139709.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(2)求四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ffc3552dd835a9ee6022bb11397a1bd.png)
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解题方法
【推荐2】如图,AB是圆O的直径,点C是圆O上异于A,B的点,
平面ABC,
,
,E,F分别为PA,PC的中点,平面BEF与平面ABC的交线为l.
平面PBC;
(2)直线l与圆O的交点为B,D,求三棱锥
的体积;
(3)点Q在直线l上,直线PQ与直线EF的夹角为
,直线PQ与平面BEF的夹角为
,是否存在点Q,使得
?如果存在,请求出
;如果不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5f1897a7e856b42f8cee0f286ad913d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/954d2fd2aecd31ff67d975bc8981023a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/02aae3ca1fa1075fa53664736707716e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9df740160690029ac1e730c85f20347.png)
(2)直线l与圆O的交点为B,D,求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2daa808ca8c95f282dae5e1d578cb65.png)
(3)点Q在直线l上,直线PQ与直线EF的夹角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48e53d0b06e3fb0338bf97042e677a23.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef2d97f14d4c63a47d142818fa29fcf4.png)
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解题方法
【推荐1】如图所示,在直三棱柱
中,E,F分别是线段AC,
的中点,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/28/40b8b996-1e9f-4f08-a037-246f380802d4.png?resizew=161)
(1)求证:平面
平面
;
(2)若
,且二面角
的余弦值为
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36f495fbead6b856fc21898c6f3d0d05.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/28/40b8b996-1e9f-4f08-a037-246f380802d4.png?resizew=161)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e51838e395dfc9d9ef597d9e01f46272.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d9a8181f7a7fe7f3fac872ce9534f15.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97f763c492745451df3c4dbcc9fcbfe3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f8c7b6766f0581fcd1ecd332afcfae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3084250c16aa160cb58887bcf6e96448.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bf513ac313cfdb6f941cb8897acbbd6.png)
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【推荐2】如图所示,在三棱锥
中,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/2021/12/29/2882847214845952/2887357543874560/STEM/d4620be93e8042439b48fdedb6f4aa68.png?resizew=170)
(1)证明:
平面
;
(2)若点
在棱
上,且二面角
为
,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47b2100b827786fab4995871c8c5816f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://img.xkw.com/dksih/QBM/2021/12/29/2882847214845952/2887357543874560/STEM/d4620be93e8042439b48fdedb6f4aa68.png?resizew=170)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3e126c16032892966489053f44b9048.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2547225b7d1f17b04a2077258be59ee7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ac09dc1ca2cdd7aef28c218763d3e4d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32d41c1e5b5d8c320ca04cacc1447465.png)
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【推荐3】四棱锥
中,底面
是边长为
的菱形,侧面
底面
,
,
,
是
中点,点
在侧棱
上.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/35fe0437-b6a4-40ad-a284-bd8c8b798ba8.png?resizew=207)
(1)求证:
;
(2)若
是
中点,求二面角
的余弦值;
(3)是否存在
,使![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
平面
?若存在,求出
的值;若不存在,说明理由.
![](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/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00ec435aa1401dbce7863b531bf2f3e5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1328e05d150f86dbe18656662eaa8f6b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/35fe0437-b6a4-40ad-a284-bd8c8b798ba8.png?resizew=207)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdfa54114f04a75b8c96165b3718ed7f.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db3a1e5f3aa16fc4009b66f6d6ac64c5.png)
(3)是否存在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/638537c0a30676c73fea76c80e0f8bd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a29292b2a3a66375202bca1fb986ecb6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d46d11e82d212c5dd76dfc0bca0399e4.png)
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解题方法
【推荐1】如图,在四棱锥
中,底面
为矩形,
⊥平面
,
.
![](https://img.xkw.com/dksih/QBM/2021/12/16/2873999653838848/2877790144413696/STEM/e286e7e1-47b3-4924-8d09-01025d6452cf.png?resizew=268)
(1)若以
为直径的圆与
相切于
点,求
与平面
所成角的正弦值;
(2)若
,在线段
上是否存在一点
,使得二面角
的余弦值为
,若存在,求二面角
的正切值;若不存在,说明理由.
![](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/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ce66c5e47598256de00e0c43adf0ebf.png)
![](https://img.xkw.com/dksih/QBM/2021/12/16/2873999653838848/2877790144413696/STEM/e286e7e1-47b3-4924-8d09-01025d6452cf.png?resizew=268)
(1)若以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f02fa4144b69d96741a476ae948def3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f4c60cb9a31fce2ff65ddd03194c8ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64f1145c162038df3c7184d9201c628e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ed479427d768bbf98c15141589109e1.png)
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【推荐2】. 如图,在三棱锥
中,
底面
,
,
,
,点
,
分别在棱
,
上,且
.
(Ⅰ)求证:
平面
;
(Ⅱ)当
为
的中点时,求
与平面
所成的角的大小;
(Ⅲ)是否存在点
使得二面角
为直二面角?并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/829f9180ddd9aa1a0ee0dc520f4e0b5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e075468e7fb0bf30229aec01a7205977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a3cc9cccfb4c260dac05f4ed57e8c10.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95a078495ba47076ccaa28b46f765d80.png)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2ffc6952e988d04f22f0fb2f7f0ab7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(Ⅱ)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(Ⅲ)是否存在点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ed479427d768bbf98c15141589109e1.png)
![](https://img.xkw.com/dksih/QBM/2012/1/11/1570685461790720/1570685467148288/STEM/742c35cd20464f0180fdc49875557a04.png?resizew=227)
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【推荐1】如图,直三棱柱
中,
,且
,
为线段
上动点.
![](https://img.xkw.com/dksih/QBM/2021/7/4/2757053906362368/2780284613410816/STEM/5008aeec-3ff5-4c59-bd8e-763ffddbb818.png?resizew=231)
(1)证明:
;
(2)判断点
到面
的距离是否为定值,并说明理由,若是定值,请求出该定值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c78404077f85ec97b51ef57fb7c75d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://img.xkw.com/dksih/QBM/2021/7/4/2757053906362368/2780284613410816/STEM/5008aeec-3ff5-4c59-bd8e-763ffddbb818.png?resizew=231)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4395b515c11b1beaec1bbb2b4f3ac25.png)
(2)判断点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07b7903de4be7d5dc1175cfbf6e8da9f.png)
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【推荐2】如图,在四棱锥
中,底面
是边长为1的正方形,
分别为
上的点,
平面
.
,求
的长;
(2)若
为
的中点,求平面
与平面
夹角的余弦值.
![](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/93fa41bdbdba9236354884eeec1c6e51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/930e85bc9f73e86cfb6ce9b076433f1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39c356f2a2155a28c928e1b67c180a35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20af148464904e21f4374cc8fb886fba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a4a6a1e70241d600bc6c104313eac61.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0bf12905647aeeded72bbca21a63f319.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b03428a8f91a5674cb8f54766c165f7e.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐3】如图,等腰直角
的斜边
为直角
的直角边,
是
的中点,
在
上,将三角形
沿
翻折,分别连接
、
、
,使得平面
平面
.已知
,
.
![](https://img.xkw.com/dksih/QBM/2023/7/25/3288509319266304/3290524248113152/STEM/a26a5e6b22a84910b5a37ab8f155d844.png?resizew=474)
(1)证明:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1384ffba86ff08ce9e783d5d1bc51686.png)
(2)若
,求平面
与平面
的夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ac451db3443cabb204f96c31fd4a02e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.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/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4eb7e9ad5486cf1c5e506b20c5469e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3d7090639341730951c1bc3c9b6164e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bb5b12692517a39c320f99a479eb055.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58899f5c3638f1e32274137723f99836.png)
![](https://img.xkw.com/dksih/QBM/2023/7/25/3288509319266304/3290524248113152/STEM/a26a5e6b22a84910b5a37ab8f155d844.png?resizew=474)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1384ffba86ff08ce9e783d5d1bc51686.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3505caf94539d51c4edba53a78ad0d3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
您最近一年使用:0次