名校
1 . 如图,多面体ABCDE中,四边形ABED是直角梯形,∠BAD=90°,DE∥AB,△ACD是的正三角形,CD=AB=
DE=1,BC=![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/d89e000f-a5b7-41ba-9631-e0638fd483ee.png?resizew=170)
(1)求证:△CDE是直角三角形
(2) F是CE的中点,证明:BF⊥平面CDE
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/d89e000f-a5b7-41ba-9631-e0638fd483ee.png?resizew=170)
(1)求证:△CDE是直角三角形
(2) F是CE的中点,证明:BF⊥平面CDE
您最近一年使用:0次
2019-01-02更新
|
232次组卷
|
2卷引用:【全国百强校】湖南省衡阳市第一中学2018-2019学年高一上学期六科联赛数学试题
2 . 在四面体ABCD中,过棱AB的上一点E作平行于AD,BC的平面分别交四面体的棱BD,DC,CA于点F,G,H
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/6/0eac358e-d7aa-4e75-b4fd-cbe363f87349.png?resizew=152)
(1)求证:截面EFGH为平行四边形
(2)若P、Q在线段BD、AC上,
,且P、F不重合,证明:PQ∥截面EFGH
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/6/0eac358e-d7aa-4e75-b4fd-cbe363f87349.png?resizew=152)
(1)求证:截面EFGH为平行四边形
(2)若P、Q在线段BD、AC上,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7071b5ecb076a09f8d128c58f01220ee.png)
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3 . (1)已知P是矩形ABCD所在平面上的一点,则有
.试证明该命题.
(2)将上述命题推广到P为空间上任一点的情形,写出这个推广后的命题并加以证明.
(3)将矩形ABCD进一步推广到长方体
,并利用(2)得到的命题建立并证明一个新命题.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a4444709816cede0c3a735af9f2ec90.png)
(2)将上述命题推广到P为空间上任一点的情形,写出这个推广后的命题并加以证明.
(3)将矩形ABCD进一步推广到长方体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd694ad3a4733c7c84aaa7946aeea4de.png)
您最近一年使用:0次
2019-01-28更新
|
311次组卷
|
3卷引用:2018年全国高中数学联赛湖南省预赛B卷
4 . 已知由
的顶点A 引出的两条射线AX 、AY 分别与 BC 交于点 X、Y.证明:
成立的充要 条件是
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f930ab785ba214b11c96a8f787a07f52.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a08ea58a49ecbbce4bd4e087c45df5f3.png)
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5 . (1)设实数
.证 明: ![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cca47dfab024c51e58a2537d95fe65b.png)
(2 )从编号为
的 100张卡片中,每次随机地抽取一张,然后放回,用这种方式连续抽取 20 次,设抽得的20个号码互不相同的概率为 P .证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fff6e7e2b9f2b68b1647f6350b98dc8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cca47dfab024c51e58a2537d95fe65b.png)
(2 )从编号为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f2dac3b86217b3f77c5c49c1e6ec2ae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1dadfe29813fde4cb14f91b9816277b.png)
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6 . 设
是正向递增的等差数列.证明:
(1)对任意的
、
,当
时,不等式
成立;
(2)对任意的
,当
时,不等式
成立.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(1)对任意的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d173e14cf43740a3fd17744ea64b0b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88ab3bf24ea24f70f98ad6ed1ecccace.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/952847e9071ad3c0716f4004ecae2e40.png)
(2)对任意的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f755f93f5eeb8721453b99432c49ffa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c972cbd63decec197aec1bdc306de67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccc50628dce827fd96199e8b4835844c.png)
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7 . 如图,
、
为椭圆
与双曲线
的公共顶点,
、
分别为双曲线和椭圆上不同于的动点,且满足
.
![](https://img.xkw.com/dksih/QBM/2018/12/4/2089521092845568/2090891703468032/STEM/5b8882285d844c1e8a5bac4b7fecacb0.png?resizew=193)
证明:(1)
、
、
三点在同一直线上;
(2)若直线
、
、
、
的斜率分别为
、
、
,则
为定值
![](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/7dd54b9df3402ad91e2d34c40efe0c7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f3fa0b40fb0d9b8c62e37316ab3b04.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b01ebd61de11f1b5910ae3225ae3755.png)
![](https://img.xkw.com/dksih/QBM/2018/12/4/2089521092845568/2090891703468032/STEM/5b8882285d844c1e8a5bac4b7fecacb0.png?resizew=193)
证明:(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
(2)若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84d454c82d9e52747563d47b68099249.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6defc43285a40f7ccb74c1cc04265eba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/423b7ae39db552e60ee8b1d27312306f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/423b7ae39db552e60ee8b1d27312306f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f626ffd69b33f9b8a7ae20d195355f1.png)
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8 . 已知互异的正实数
、
、
、
满足
.
证明:从
、
、
、
中任取三个数作为边长,共可构成四个不同的三角形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c814128ea2139e33db94ea590e7c2223.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aec19b68e3add9d5bfcc6269a1855b87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/291c25fc6a69d6d0ccfb8d839b9b4462.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/365b38a7689a8eede6820cd6f1fe952b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c570c70a0b68cdedd9f14e972299f8e5.png)
证明:从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c814128ea2139e33db94ea590e7c2223.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aec19b68e3add9d5bfcc6269a1855b87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/291c25fc6a69d6d0ccfb8d839b9b4462.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/365b38a7689a8eede6820cd6f1fe952b.png)
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2001高三·湖南·竞赛
9 . 边长为1的菱形
的两对角线交于
,过
作A2B2∥A1B1交
于
连结
交
于
,过
作A3B3∥A1B1交
于
,…,这样作下去得
以
为原点,
所在直线为
轴,建立平面直角坐标系,设以
为半径,圆心在
,轴上的一列圆
依次相外切(即
与
外切,
),若圆T1与抛物线
相切.求证:所有的圆
都与抛物线
相切.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fb04914c4e8fb3483da44c67fe1809f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3b9e816b14051f785aa5aae72b8eed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3b9e816b14051f785aa5aae72b8eed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7f6f93171329d508d491143b9d71f7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43a71fc9c0068109dad1382354570665.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5e1bca493e452800f697c5c640b4aa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ee8456443402a25b1e25d35ff7e1c98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04b56e44e4f0424a2b7a45567120a2e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04b56e44e4f0424a2b7a45567120a2e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7f6f93171329d508d491143b9d71f7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2857fac4963b129d99e79dcb3e13d295.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/374cb268ffa23fc0bf12c6e6dc873c4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7f6f93171329d508d491143b9d71f7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edd95334c0f28db6ab76e6e6a3df88bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e1297f1f7cbc86fe8ce78115bbce249.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a996c4e29bcc381353e072eb04c11b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9714efed34e3ccc08351e915b64df80e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3dd310f7760a862ab1938e5d97eeac97.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/344ccbf79da6ad7e3709d6fa72efb756.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e1297f1f7cbc86fe8ce78115bbce249.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/344ccbf79da6ad7e3709d6fa72efb756.png)
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10 . 设
.证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23d4e011d62bfd8f486c2e4314fceca7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd1cdfcc579d5733f09d1be556a88993.png)
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