1 . 请选择适当的方法证明下列结论:
(1)求证:
;
(2)已知
,求证:
.
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0c1d583e670dac4530bd57ac9118740.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a0c4c098615c6bc7e6dcf72e5b5201a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6e10cc5dd849caccce37fe98a26c598.png)
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21-22高三上·黑龙江哈尔滨·阶段练习
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2 . 如图,在直三棱柱
中,
,
,
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a98332901058e22626af97bff1b71039.png)
![](https://img.xkw.com/dksih/QBM/2021/2/19/2661504202792960/2661637481037824/STEM/62472c22-ab1a-4588-a0e1-7d5569c19892.png)
(1)证明:当
时,求证:
平面
;
(2)当
时,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/615fc8790237a1b09af51d6bcad6b595.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7ad3a578f403b9e6b97fa2dc955fc11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a98332901058e22626af97bff1b71039.png)
![](https://img.xkw.com/dksih/QBM/2021/2/19/2661504202792960/2661637481037824/STEM/62472c22-ab1a-4588-a0e1-7d5569c19892.png)
(1)证明:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73b3cf0f585938ede9eca890a6eb326d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6d06903252260d31d1a9cdeb735b089.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8845fadc307f1d308410e829becedd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78ceb31247add8ca7b0853e801e1d125.png)
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解题方法
3 . 如图所示
,
,侧面
底面
若
.
![](https://img.xkw.com/dksih/QBM/2021/1/5/2629475259146240/2632465580244992/STEM/6c14c863-eed0-4976-908e-903062322c2d.png?resizew=249)
(1)求证:
平面PAC;
(2)侧棱PA上是否存在点E,使得
平面PCD?若存在,指出点E的位置并证明,若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef699f5dc072b853cfe700c6f1abbbae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1141247167a3d1584ae774f3fb164321.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebbb79892c8cb8871a08437acc09bc80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/702f9d7ff83e48e10187bd66b45beecb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3af3d91d89c75231ba82c9cf6aff92a6.png)
![](https://img.xkw.com/dksih/QBM/2021/1/5/2629475259146240/2632465580244992/STEM/6c14c863-eed0-4976-908e-903062322c2d.png?resizew=249)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28fa14d4841ca3f2fe226688c25c8160.png)
(2)侧棱PA上是否存在点E,使得
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5258a6f9c63914b9e2ec95b6d39313b2.png)
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4 . 用反证法证明“设
,求证
”时,第一步的假设是______________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/127a0d8c1c7d15ed40ec4b8bca0ebdf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/485a2d99320384a0857b00ce9ab9e990.png)
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2020-03-20更新
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5 . (1)求证
.
(2)设x,y都是正数,且x+y>2证明:
和
中至少有一个成立.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ffe492bb9af2b14bac592bbc72cd3d.png)
(2)设x,y都是正数,且x+y>2证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe6efd706e0d6fd5921c8ba41866c8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/994a46413196d5150c865507aea411ae.png)
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【全国百强校】宁夏回族自治区平罗中学2018-2019学年高二下学期期中考试数学(文)试题2019届陕西省宝鸡市宝鸡中学高三上学期10月第一次模拟考试数学(文)试题(A卷)河南省周口市郸城县实验高中2019-2020学年高二下学期第二次月考数学(理)试题河南省新乡市辉县市第二高级中学2019-2020学年高二下学期期中考试数学(理)试题河南省新乡市辉县市第二高级中学2019-2020学年高二下学期期中考试数学(文)试题安徽省安庆市第十中学2020-2021学年高二下学期第一次月考文科数学试题安徽省芜湖市第一中学2020-2021学年高二下学期期中理科数学试题山西省晋中市新一双语学校2020-2021学年高二下学期3月月考数学(理)试题河南省新乡市河南师大附中实验学校2021-2022学年高二下学期期中考试数学文科试题
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6 . 已知△
中,
,求证
.
证明:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf7efa75e1f580910d41d954bc911cd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0caa3e6a0de075df4c9a869dfed4bf20.png)
画线部分是演绎推理的( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37c0ad68bf0ca0d00461a269df127af5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6a46e678bf9d2df5ad4c782b3dc22f5.png)
证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf7efa75e1f580910d41d954bc911cd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0caa3e6a0de075df4c9a869dfed4bf20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bf1aa83a61bd003e09b68d51af984a4.png)
A.大前提 | B.三段论 | C.结论 | D.小前提 |
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2017-07-15更新
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3卷引用:宁夏石嘴山市第三中学2017-2018学年高二上学期期末考试数学(文)试题
7 . 已知数列
满足
,
,数列
满足
,
.
(1)证明:
为等比数列;
(2)数列
满足
,求数列
的前
项和
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b13a6e1d671215fc96e4bee3541d1096.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b973cef9460d84bec30961a9d3443cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/385275d29d8c8a7841eaeaa3dfab2cdb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c94e7e73992aa9ff5b779b1d382671a.png)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b7bb5000adef715be512d2ce5ee66f9.png)
(2)数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38ef4c4439b36c2847b0056a116d56d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4918e780861d676138eb35a9e7cb5c6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38ef4c4439b36c2847b0056a116d56d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83d76c3eb0a07a827877d7a4dc306211.png)
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8 . 选择适当的方法证明.
已知:
,求证:
.
已知:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9185519a1b1928d6cd4147f43c738145.png)
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2卷引用:宁夏海原第一中学2020-2021学年高二下学期第二次月考数学(文)试题
9 . 如图,在四棱锥
中,底面
是边长为a的正方形,侧面
底面
,且
,设E,F分别为
,
的中点.
平面
;
(2)求直线
与平面
所成角的大小.
![](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/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1e030853e53547cc35df6ee1e033beb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4aa9084b8fe0fe05c4388d1f835587b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/218054144a13435580cd132b9459546c.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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10 . 如图,在三棱柱
中,
,
,侧面
是正方形,
为
的中点,二面角
的大小是
.
平面
;
(2)线段
上是否存在一个点
,使直线
与平面
所成角的正弦值为
.若存在,求出
的长;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5ae8a050d7159d4296c2409e5bc0bf8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef0402dd5ae3db10281f9f1e11738bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cea67423ce6963c0972867306169f17a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0211da37e92f915e781691296578ba0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/589024e3c65475d8b5b00ebf373e4965.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)线段
![](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/e516121599c9fcc528121c00afcf52fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d9a8181f7a7fe7f3fac872ce9534f15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4df730e937fb61b85054d316848b304.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
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