对于椭圆
,令
,
,那么在坐标系
中,椭圆经伸缩变换得到了单位圆
,在这样的伸缩变换中,有些几何关系保持不变,例如点、直线、曲线的位置关系以及点分线段的比等等;而有些几何量则等比例变化,例如任何封闭图形在变换后的面积变为原先的
,由此我们可以借助圆的几何性质处理一些椭圆的问题.
(1)在原坐标系中斜率为k的直线l,经过
,
的伸缩变换后斜率变为
,求k与
满足的关系;
(2)设动点P在椭圆
上,过点P作椭圆
的切线,与椭圆
交于点Q,R,再过点Q,R分别作椭圆
的切线交于点S,求点S的轨迹方程;
(3)点
)在椭圆
上,求椭圆上点B,C的坐标,使得△ABC的面积取最大值,并求出该最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8429aec72d26401b12a55b8337261df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/070cb835e194f9bb99aba9daf58bd2b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50443405ab95a95149c68f59f96619de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/863b5f9f0a7c6b7956979a5abc76d8d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e08c4a230e32f550374a5fa4db5f204.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/848d4055ca831ecde46d1b666ba9e33d.png)
(1)在原坐标系中斜率为k的直线l,经过
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/070cb835e194f9bb99aba9daf58bd2b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50443405ab95a95149c68f59f96619de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbc8ced3660dab6e343773fd9dccebc3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbc8ced3660dab6e343773fd9dccebc3.png)
(2)设动点P在椭圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/841307fdcdbbccacd07b652db535631f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce30fc0664cca88dbe6d38f32aee81e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd76519af3c3a098a590ad302acc003b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aaafb050b24c4e806c480e0665aaa5a.png)
(3)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad492d5033448d419df9c9b75a71894e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/271e595c257e4c0ade90a9bbbf0e6b0d.png)
更新时间:2024-05-20 21:14:12
|
相似题推荐
【推荐1】在平面直角坐标系xOy中,直线l:
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解题方法
【推荐2】已知圆心在
轴上移动的圆经过点
,且与
轴、
轴分别交于
、
两个动点,过点
垂直于
轴的直线与过点
垂直于
轴的直线交于点
.
(1)求点
的轨迹
的方程;
(2)点
、
在曲线
上,以
为直径的圆经过原点
,作
,垂足为
.试探究是否存在定点
,使得
为定值,若存在,求出该定点
的坐标;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61c87b7e39ab4c173e357d92f345ddab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
(1)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
(2)点
![](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/0b68df477b3ee45ac0f725db00d465a1.png)
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【推荐1】已知椭圆
的右焦点为
,点
在椭圆
上.
(1)求椭圆
的方程;
(2)过
的两条互相垂直的直线分别交椭圆
于
两点和
两点,设
的中点分别为
,求
面积的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/851a5d6ec23256f9b4a9e98aa92945fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be92f0e0012a7696c78e3e00513edefd.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(1)求椭圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(2)过
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b487a48fb03928254b978f9245418515.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecfb02e157819a2bdd0f2790cbc825e9.png)
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【推荐2】已知椭圆
,若椭圆的短轴长为
且经过点
,过点
的直线交椭圆于P,Q两点.
(1)求椭圆方程;
(2)求
面积的最大值,并求此时直线
的方程;
(3)若直线
与x轴不垂直,在x轴上是否存在点
使得
恒成立?若存在,求出s的值;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad523e69a1bf925e73a22900b9855df2.png)
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(1)求椭圆方程;
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1f0417d8269f01d8e0bc1a8756e2ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
(3)若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
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解题方法
【推荐1】斜二测画法是一种常用的工程制图方法,在已知图形中平行于
轴的线段,在直观图画成平行于
轴(由
轴顺时针旋转
得到)的线段,且长度为原来的
,平行于
轴的线段不变.如图,在直角坐标系
中,正方形
的边长为
.定义如下图像变换:
表示“将图形用斜二测画法变形后放回原直角坐标系”;
表示“将图形的横坐标保持不变,纵坐标拉伸为原来的
倍”.
经过两次
变换后所得图形为
,求
的坐标;
(2)在第
次复合变换中,将图形先进行一次
变换,再进行一次
变换,
. 记正方形
进行
次复合变换后所得图形为
.过
作
的垂线,垂足为
,若
恒成立,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
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(2)在第
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c05b9832b09731a574d4a4adf7448de.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a8c8bb5b1ee645a5e94c72823b5f295.png)
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名校
【推荐2】在平面直角坐标系
中,对于任意一点
,总存在一个点
满足关系式
,则称
为平面直角坐标系中的伸缩变换.
(1)在同一直角坐标系中,求平面直角坐标系中的伸缩变换
,使得椭圆
变换为一个单位圆;
(2)在同一直角坐标系中,
(
为坐标原点)经平面直角坐标系中的伸缩变换
得到
,记
和
的面积分别为
与
,求证:
;
(3)若
的三个顶点都在椭圆
上,且椭圆中心恰好是
的重心,求
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aee82283f06cedef32eb15b87964f5d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/495984a7f99222eb03bf296260fac7b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/882fe79977fce2cc7c289b0da1721c2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6581916f5a65edfea257c804efee007e.png)
(1)在同一直角坐标系中,求平面直角坐标系中的伸缩变换
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe4f007b1ceaccfff1d659f6f8592c4e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78847dd23bb54d5d960016e6beeb5713.png)
(2)在同一直角坐标系中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/866b81a8384cce4f24867baca2e6820c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/882fe79977fce2cc7c289b0da1721c2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a21e44af368f3336354704d92609f9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/866b81a8384cce4f24867baca2e6820c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a21e44af368f3336354704d92609f9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/150a135bbd528daf3f19a58a621a57c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/793b3bfc799e7cd6a795324ca02aaa23.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36e5e61804ce550636a0354e0a78a22d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48da128547c4cf9745e8e4b99988a3db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36e5e61804ce550636a0354e0a78a22d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36e5e61804ce550636a0354e0a78a22d.png)
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