解题方法
1 . 用平面截圆锥面,可以截出椭圆、双曲线、抛物线,那它们是不是符合圆锥曲线的定义呢?比利时数学家旦德林用一个双球模型给出了证明.如图1,在一个圆锥中放入两个球,使得它们都与圆锥面相切,一个平面过圆锥母线上的点
且与两个球都相切,切点分别记为
.这个平面截圆锥面得到交线
是
上任意一点,过点
的母线与两个球分别相切于点
,因此有
,而
是图中两个圆锥母线长的差,是一个定值,因此曲线
是一个椭圆.如图2,两个对顶圆锥中,各有一个球,这两个球的半径相等且与圆锥面相切,已知这两个圆锥的母线与轴夹角的正切值为
,球的半径为4,平面
与圆锥的轴平行,且与这两个球相切于
两点,记平面
与圆锥侧面相交所得曲线为
,则曲线
的离心率为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d2a97987f71835f519b462f5b8f5957.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c0f067a2a348ceb24a408f82992eab8.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d599cb4a589f90b0205f24c2e1fa021e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.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)
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解题方法
2 . 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
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3 . 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
|
1178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