11-12高二下·云南昆明·期中
解题方法
1 . 如图所示,在直三棱柱
中,
,
,棱
上有两个动点
,且
(
为常数).
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/15/bfda8026-b351-47f5-8f5b-458255e8c16c.png?resizew=154)
(1)在平面
内确定一条直线,使该直线与直线
垂直;
(2)判断三棱锥
的体积是否为定值.若是定值,求出这个三棱锥的体积;若不是定值,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8684078379a9e6b209068e1de693af0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbf8e8f0f906ffe9a7a1002bfba4c5ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af260e0d98c95d1e092dc4c6d348e3ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3f4d1da8f44703de3db704ea611cfca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad056c25c0fdcbcc765eb5cbc6093f2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3319509bbd6b74f077bc88681d7be74d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/15/bfda8026-b351-47f5-8f5b-458255e8c16c.png?resizew=154)
(1)在平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
(2)判断三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/209e3b87346e057276f0692a7361e446.png)
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2012高二·辽宁·学业考试
2 . 已知一条曲线上的点到定点
的距离是到定点
距离的二倍,求这条曲线的方程.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1a9821a00b71f6b7d7a76d91b3f810.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f2b1f4120365cb6ee4925fe417563f9.png)
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