木马速递
幼苗
共回答了19个问题采纳率:89.5% 举报
(Ⅰ)
![](https://img.yulucn.com/upload/0/5e/05e41ebb5fd2997d2397662f80f01f4f_thumb.jpg)
(Ⅱ)
![](https://img.yulucn.com/upload/e/b5/eb542b5f2dfeac73057e49138be8eb09_thumb.jpg)
,或
![](https://img.yulucn.com/upload/8/a9/8a9bc83616c114bdda525bbd07bad045_thumb.jpg)
,或
![](https://img.yulucn.com/upload/5/87/587f8c01e5458a11a0148362e743c1d9_thumb.jpg)
,或
![](https://img.yulucn.com/upload/c/e4/ce4232f95a582f354bc30fd22645e628_thumb.jpg)
.
(Ⅰ)由
![](https://img.yulucn.com/upload/3/6a/36a34192fc8d4e1e69e3dabed82bbddc_thumb.jpg)
,得
![](https://img.yulucn.com/upload/c/f6/cf6390874bd797571db698b68a2885f5_thumb.jpg)
.故圆C的圆心为点
![](https://img.yulucn.com/upload/9/3e/93e202e26e10e790979366f60e7db9cb_thumb.jpg)
从而可设椭圆E的方程为
![](https://img.yulucn.com/upload/1/e4/1e420dbfa8999bafbcaf58ca390f6422_thumb.jpg)
其焦距为
![](https://img.yulucn.com/upload/4/e0/4e0318f43c7f91fde8f955012d72815e_thumb.jpg)
,由题设知
![](https://img.yulucn.com/upload/d/ca/dca140a67d4602705b87cab3a166df32_thumb.jpg)
故椭圆E的方程为:
(Ⅱ)设点
![](https://img.yulucn.com/upload/c/1f/c1f9c2e80258c03cf23d3219b306921a_thumb.jpg)
的坐标为
![](https://img.yulucn.com/upload/1/1d/11d4b842dec513526d0430d782808364_thumb.jpg)
,
![](https://img.yulucn.com/upload/1/6e/16e36690b84c25ef17b53bfbbd53f26c_thumb.jpg)
的斜分率分别为
![](https://img.yulucn.com/upload/c/1e/c1eeefa8829212f29c97894812188cd2_thumb.jpg)
则
![](https://img.yulucn.com/upload/1/6e/16e36690b84c25ef17b53bfbbd53f26c_thumb.jpg)
的方程分别为
![](https://img.yulucn.com/upload/2/48/2485f7f8dbe82f989f468d2b4e7cdcf5_thumb.jpg)
且
![](https://img.yulucn.com/upload/6/b0/6b06e99431faeb07d6d6ed5ddde7e722_thumb.jpg)
由
![](https://img.yulucn.com/upload/7/72/772aa2457bff05b9e91aeaeba13c0f1b_thumb.jpg)
与圆
![](https://img.yulucn.com/upload/b/15/b156a3b1df291006f3fed353cee89666_thumb.jpg)
相切,得
![](https://img.yulucn.com/upload/2/01/20143bdf87669befb7f113998a264aa7_thumb.jpg)
,即
同理可得
![](https://img.yulucn.com/upload/c/14/c146b8c7e728143ac9368ed31b464d25_thumb.jpg)
.
从而
![](https://img.yulucn.com/upload/1/d1/1d174f9c72778cb7836bf5256758bcb6_thumb.jpg)
是方程
![](https://img.yulucn.com/upload/2/9c/29c294cfb2d34ac05d1d9f4d8e5f5e96_thumb.jpg)
的两个实根,于是
![](https://img.yulucn.com/upload/9/4c/94ccb3c9f6d89042961eeb5078ddae13_thumb.jpg)
①
且
由
![](https://img.yulucn.com/upload/d/ea/dea41cb173174fa28b103d9c4473cb5e_thumb.jpg)
得
![](https://img.yulucn.com/upload/e/3f/e3f9eab7f48db3b2becd43dcdb6f9e44_thumb.jpg)
解得
![](https://img.yulucn.com/upload/e/90/e902bb72326381427563bb25a3140e1d_thumb.jpg)
或
由
![](https://img.yulucn.com/upload/3/ed/3ed85cef8d0875f1a6137b812bfba48a_thumb.jpg)
得
![](https://img.yulucn.com/upload/2/d9/2d95d9b52b80d040dd767d11b61bfbce_thumb.jpg)
由
![](https://img.yulucn.com/upload/0/54/0544f2d8aac11ca0ccf9242135835634_thumb.jpg)
得
![](https://img.yulucn.com/upload/c/c9/cc953ad20795b5c57577b4e8f1c14cc1_thumb.jpg)
它们满足①式,故点P的坐标为
![](https://img.yulucn.com/upload/e/b5/eb542b5f2dfeac73057e49138be8eb09_thumb.jpg)
,或
![](https://img.yulucn.com/upload/8/a9/8a9bc83616c114bdda525bbd07bad045_thumb.jpg)
,或
![](https://img.yulucn.com/upload/5/87/587f8c01e5458a11a0148362e743c1d9_thumb.jpg)
,或
![](https://img.yulucn.com/upload/c/e4/ce4232f95a582f354bc30fd22645e628_thumb.jpg)
.
【点评】本题考查曲线与方程、直线与曲线的位置关系,考查运算能力,考查数形结合思想、函数与方程思想等数学思想方法.第一问根据条件设出椭圆方程,求出
![](https://img.yulucn.com/upload/4/7f/47f17a525275f968c474150ce446263f_thumb.jpg)
即得椭圆E的方程,第二问设出点P坐标,利用过P点的两条直线斜率之积为
![](https://img.yulucn.com/upload/f/01/f012c42fac29d573c55ab7bb2f3a70ef_thumb.jpg)
,得出关于点P坐标的一个方程,利用点P在椭圆上得出另一方程,联立两个方程得点P坐标.
1年前
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