1 . 关于问题“从区间
内随机地取两个数x,y,求x,y满足
的概率”,有一种解法是:在平面直角坐标系内,条件
表示的区域为边长
的正方形,面积
;所求
表示的区域为半径
的圆的
,面积
,则所求概率
.类比上述解法,我们可求得:从区间
内随机地取三个数x,y,z,则x,y,z满足
的概率为___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/304226ca50149b49702928e44d565964.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dccf7fdc9ff5e9e6ed897ec3a716a35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b3c012fe79ce5c4b7ff30dac73c5a41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b550ee821ee1838384835e81fc34b67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9c752ebe8516e7d3327f3410473d9a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5529f8149d6ea5ad04323f4676b2112.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7551011cfb75b26f35b07d6617c6a18b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d266a04f3dc7483eddbc26c5e487db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b4bd12fc54469e386724bb367282c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72d36e1beb36c5f70fd69fdcdb599c59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/304226ca50149b49702928e44d565964.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5e7d952a3e4538803ad8e142a16104.png)
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2023-02-28更新
|
100次组卷
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2卷引用:重庆市巴蜀中学校2020届高三下学期5月月考文科数学试题
名校
解题方法
2 . 如图1,与三角形的三边都相切的圆叫做三角形的内切圆.设O是△ABC的内切圆圆心,
内是△ABC的内切圆半径,设
是△ABC的面积,
是△ABC的周长,由等面积法,可以得到
内
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/e3da696e-d797-4178-ab24-f0087aafa165.jpg?resizew=358)
(1)与三棱锥的四个面都相切的球叫做三棱锥的内切球.设三棱锥的体积是
,表面积是
,请用类比推理思想,写出三棱锥的内切球的半径公式
内(只写结论即可,不必写推理过程);
(2)如图2,在三棱锥
中,
,
,
两两垂直,且
,求三棱锥
的内切球半径和外接球的半径之比.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5cbff84327e964f912a54032e76ccc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8c261982132e55c19fd25ad50c6f3b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4fcc80a88cb1dc8fd4184f5b8225814.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/e3da696e-d797-4178-ab24-f0087aafa165.jpg?resizew=358)
(1)与三棱锥的四个面都相切的球叫做三棱锥的内切球.设三棱锥的体积是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
(2)如图2,在三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50094bfee564d9c1b03088ac2ece28c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
您最近一年使用:0次
2021-12-29更新
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442次组卷
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3卷引用:广东省佛山市顺德区高中联盟2019-2020学年高二上学期第一次联考数学试题