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)
20-21高二上·江苏盐城·期末 查看更多[2]
更新时间:2021-01-30 11:18:38
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【推荐1】已知等边
的边长为2,将其沿边
旋转到如图所示的位置,此时点
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在同一球面上,且
,则该球的表面积为___________ .
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【推荐2】已知直线
与球
有且只有一个公共点 ,从直线
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的平面角为
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的表面积等于______ .
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【推荐1】已知椭圆
的右焦点
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48da128547c4cf9745e8e4b99988a3db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
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【推荐2】已知椭圆
的左焦点为
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斜率为
的直线
与椭圆
相交于
、
两点,若
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的离心率![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47ce2b47812fce4b17fd813d0e4cce21.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7d72a07a4e5acfc140a3cea1f26b951.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
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【推荐3】某中学开展“劳动创造美好生活”的劳动主题教育活动,展示劳动实践成果并进行评比,某学生设计的一款如图所示的“心形”工艺品获得了“十佳创意奖”,该“心形”由上、下两部分组成,并用矩形框
虚线
进行镶嵌,上部分是两个半径都为
的半圆,
分别为其直径,且
,下部分是一个“半椭圆”,并把椭圆的离心率叫做“心形”的离心率.
,则当该矩形框面积最大时,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/258e40e3883271c3580c1d3c805dcac6.png)
__________ ;
(2)若
,图中阴影区域的面积为
,则该“心形”的离心率为__________ .
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(2)若
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