名校
解题方法
1 . 假设视网膜为一个平面,光在空气中不折射,眼球的成像原理为小孔成像. 思考如下成像原理: 如图,地面内有圆
,其圆心在线段
上,且与线段
交于不与
重合的点
,
地面,且
,
点为人眼所在处,视网膜平面与直线
垂直. 过
点作平面
平行于视网膜平面. 科学家已经证明,这种情况下圆
上任意一点到
点的直线与平面
交点的轨迹(令为曲线
)为椭圆或圆,且由于小孔成像,曲线
与圆
在视网膜平面上的影像是相似的,则当视网膜平面上的圆
的影像为圆时,圆
的半径
为____________ . 当圆
的半径
满足
时,视网膜平面上的圆
的影像的离心率的取值范围为____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5c62f22d7afc5627fcb86599faa8e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5c62f22d7afc5627fcb86599faa8e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/137d33c8575602cb3480ba3825dece9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a7442b64b37f685bc3ae88ff450c1a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70e92e4810c9461c39fae1acde95e489.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3dc6893e52bbca0d011ac46845334d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
您最近一年使用:0次
2024-05-09更新
|
99次组卷
|
2卷引用:四川省成都市实验外国语学校2023-2024学年高二上学期期末能力测评数学试题
名校
解题方法
2 . 我们常常运用对同一个量算两次的方法来证明组合恒等式,如:从装有编号为
的
个球的口袋中取出
个球
,共有
种取法.在
种取法中,不取
号球有
种取法;取
号球有
种取法.所以
.试运用此方法,写出如下等式的结果:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b755a1a0fb8df7d9bc558ee7f9e3323c.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5ffc1f6e06cbd6f8892ea654fe76c83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb3e2f42388d6162a04a91165db79c66.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ab4717e4827480f0f6f4ded85e52eab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f1283c06a7f7cbc5f050482f0af11f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e0c2fc8acf474854b377bc0375afc15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e0c2fc8acf474854b377bc0375afc15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/414656636a840bbb9a031d6103239fdd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7707aba7b9fed2c8e4704b82ce09087a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/414656636a840bbb9a031d6103239fdd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06bbbb77531a69594c20afa2cff2d723.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd1dce2b1d61c2e26cee7c8b75a104be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b755a1a0fb8df7d9bc558ee7f9e3323c.png)
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2022-10-17更新
|
1616次组卷
|
9卷引用:浙江省强基联盟2022-2023学年高二实验班上学期10月联考数学试题
浙江省强基联盟2022-2023学年高二实验班上学期10月联考数学试题(已下线)6.2.3-6.2.4 组合 组合数(练习)-2022-2023学年高二数学同步精品课堂(人教A版2019选择性必修第三册)(已下线)7.3 组合(练习)-2022-2023学年高二数学同步精品课堂(苏教版2019选择性必修第二册)江苏省常州市第一中学2023-2024学年高二上学期期末质量调研数学试题(已下线)专题01 两个计数原理与排列组合(7类压轴题型)-【常考压轴题】2023-2024学年高二数学压轴题攻略(人教A版2019选择性必修第三册)(已下线)专题20 计数原理(讲义)-1辽宁省丹东市五校2022-2023学年高三上学期联考数学试题辽宁省沈阳市东北育才学校2023届高三高考适应性测试(二)数学试题(已下线)专题18 排列组合与二项式定理
名校
解题方法
3 . 如图,在直角坐标系
中,圆
:
与
轴负半轴交于点
,过点
的直线
,
分别与圆
交于
,
两点,设直线
、
的斜率分别为
、
.
![](https://img.xkw.com/dksih/QBM/2020/11/5/2586652209078272/2587853242482688/STEM/93cadeda-1b59-493e-9c84-4b03fb3ce1a7.png?resizew=220)
(1)若
,
,求
的面积;
(2)若
,求证:直线
过定点.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5f5d967ad135991b6075ee45df55643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50b3ae183997b707d16eb4e7f6712fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50b3ae183997b707d16eb4e7f6712fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6defc43285a40f7ccb74c1cc04265eba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/423b7ae39db552e60ee8b1d27312306f.png)
![](https://img.xkw.com/dksih/QBM/2020/11/5/2586652209078272/2587853242482688/STEM/93cadeda-1b59-493e-9c84-4b03fb3ce1a7.png?resizew=220)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd16710e91b25f9850efacebd299c9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8ff4f8895f1bc0d70524364a0a735f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98013a5042685a1db94249e70c62c09a.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d0b20880f4f6120dca1efdec01cbd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
您最近一年使用:0次
2020-11-07更新
|
297次组卷
|
2卷引用:江西省赣州市南康中学2020-2021学年高二上学期第二次大考数学(理)试题
4 . 在学习推理和证明的课堂上,老师给出两个曲线方程
;
,老师问同学们:你想到了什么?能得到哪些结论?下面是四位同学的回答:
甲:曲线
关于
对称;
乙:曲线
关于原点对称;
丙:曲线
与坐标轴在第一象限围成的图形面积
;
丁:曲线
与坐标轴在第一象限围成的图形面积
;
四位同学回答正确的有______ (选填“甲、乙、丙、丁”).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5bc0aceabda0f5389edf22aa2760611.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e81c9cb1eae36ed4f56921297414dd52.png)
甲:曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1241216f3c1cb5e73043dd1037f556d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d77f5191798242b7b9b88a75e17e4425.png)
乙:曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f3ffe7abc59e2f65d827c8eab8d36a.png)
丙:曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1241216f3c1cb5e73043dd1037f556d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/585709cb7afdaa0127f466c45e42883d.png)
丁:曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f3ffe7abc59e2f65d827c8eab8d36a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dda39bb5036643597d7aabfa602e9854.png)
四位同学回答正确的有
您最近一年使用:0次
2021-04-14更新
|
625次组卷
|
5卷引用:广西玉林市2020-2021学年高二下学期期末数学(文)试题
广西玉林市2020-2021学年高二下学期期末数学(文)试题广西玉林市2020-2021学年高二下学期期末数学(理)试题东北三省四市教研联合体2021届高三第二次联合考试理科数学试题东北三省三校(哈师大附中、辽宁省实验中学、东北师范大学附属中学)2021届高三二模数学(理)试题(已下线)考点45 曲线与方程-备战2021年高考数学经典小题考前必刷(新高考地区专用)
5 . 如图是数学家
用来证明一个平面截圆锥得到的截面是椭圆的模型(称为丹德林双球模型):在圆锥内放两个大小不同的小球,使得它们分别与圆锥侧面、截面相切,设图中球
和球
的半径分别为1和3,
,截面分别与球
和球
切于点
和
,则此椭圆的长轴长为___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b46aeafa272f1c63107d934a82c3f49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4f6f74444b2b7947fc6e35c8d62322.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1014fd8ecfe71ec4c366496e2dd2c238.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4f6f74444b2b7947fc6e35c8d62322.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/2021/1/29/2646475190992896/2647177162899456/STEM/87a2ad6999e64b6e9562284557f97388.png?resizew=116)
您最近一年使用:0次
名校
6 . 1611年,约翰内斯·开普勒提出了“没有任何装球方式的密度比面心立方与六方最密堆积要高”的猜想.简单地说,开普勒猜想就是对空间中如何堆积最密圆球的解答.2017年,由匹兹堡大学数学系教授托马斯·黑尔斯(Thomas Hales)带领的团队发表了关于开普勒猜想证明的论文,给这个超过三百年的历史难题提交了一份正式的答案.现有大小形状都相同的若干排球,按照下面图片中的方式摆放(底层形状为等边三角形,每边4个球,共4层),这些排球共__________ 个,最上面球的球顶距离地面的高度约为__________
(排球的直径约为
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efa9fbcfb9595e2f031aa691db4564b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d2eb8ac733873fb3e728399ac856f16.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/8/0c87873d-c7f2-4a40-aad6-fc2f10261701.png?resizew=133)
您最近一年使用:0次
2020-04-24更新
|
427次组卷
|
2卷引用:江苏省南通市海安县曲塘中学2020-2021学年高二上学期阶段性测试二数学试题
名校
7 . 组合恒等式
,可以利用“算两次”的方法来证明:分别求
和
的展开式中
的系数.前者
的展开式中
的系数为
;后者
的展开式
中
的系数为
.因为
,则两个展开式中
的系数也相等,即
.请用“算两次”的方法化简下列式子:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89a5da8ca5f9f82b603a776cf7c047e2.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0a27dc7f3952c6b6a11376205e7026f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5da7bfad011650578d8d6932e040c108.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abcb23d99fdb65d7a60cae3aa4364a89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbc1fb81fa5b128500c08c9593d6a89e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5da7bfad011650578d8d6932e040c108.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbc1fb81fa5b128500c08c9593d6a89e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e8e1995ad54cd7c9ddfd43dab19b1ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abcb23d99fdb65d7a60cae3aa4364a89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f2832587e638ed851652d60ca716b8d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbc1fb81fa5b128500c08c9593d6a89e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/445a256f8985606f98f015d84b36b691.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/663c307dad10414d54127f8ebef28a75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbc1fb81fa5b128500c08c9593d6a89e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0a27dc7f3952c6b6a11376205e7026f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89a5da8ca5f9f82b603a776cf7c047e2.png)
您最近一年使用:0次
2019-07-01更新
|
1177次组卷
|
2卷引用:江西省南昌市八一中学、洪都中学、麻丘高中等七校2018-2019学年高二下学期期末考试数学(理)试题
8 . 设向量
,
,其中
,
,
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
,由不等式
恒成立,可以证明柯西不等式
(当且仅当
,即
时等号成立).已知
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
,若
恒成立,利用柯西不等式可求得实数
的取值范围为________________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a0fb4d6477160c8964034ca02de3b56.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/557ca73405c6884f688c46ee8daad7ef.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/5c02bc0c74292b1e8f395f90935d3174.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/160daec0ad9ccc242f3e259eb4d61ef6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51ac29b9c6ad0825a3f0e8489c10a4d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f0c314051906863d6c9502fb3faf585.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bf91d09e73dec24c2f764d421ad64ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd68c14adb3cf12d8f77aec55a053284.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b03f2fbdd3eee86346e04ddee66b2f8d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/881b614a0277c307159db0f8178fc39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
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