解题方法
1 . 青花瓷又称白地青花瓷,常简称青花,中华陶瓷烧制工艺的珍品,是中国瓷器的主流品种之一,属釉下彩瓷.如图为青花瓷大盘,盘子的边缘有一定的宽度且与桌面水平,可以近似看成由大小两个椭圆围成.经测量发现两椭圆的长轴长之比与短轴长之比相等.现不慎掉落一根质地均匀的长筷子在盘面上,恰巧与小椭圆相切,设切点为
,盘子的中心为
,筷子与大椭圆的两交点为
、
,点
关于
的对称点为
.给出下列四个命题:
①两椭圆的焦距长相等;
②两椭圆的离心率相等;
③
;
④
与小椭圆相切.
其中正确的个数是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/27/b0dab7ba-ec54-4f03-87b0-4b1dc37f5fa1.png?resizew=191)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](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/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
①两椭圆的焦距长相等;
②两椭圆的离心率相等;
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f30acc34f4ee1077532ae6808af2ab2.png)
④
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
其中正确的个数是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/27/b0dab7ba-ec54-4f03-87b0-4b1dc37f5fa1.png?resizew=191)
A.![]() | B.![]() | C.![]() | D.![]() |
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