名校
解题方法
1 . 球面几何学是在球表面上的几何学,也是非欧几何的一个例子.对于半径为R的球
,过球面上一点
作两条大圆的弧
,
,它们构成的图形叫做球面角,记作
(或
),其值为二面角
的大小,点
称为球面角的顶点,大圆弧
称为球面角的边.不在同一大圆上的三点
,可以得到经过这三点中任意两点的大圆的劣弧
,这三条劣弧组成的图形称为球面
,这三条劣弧称为球面
的边,
三点称为球面
的顶点;三个球面角
称为球面
的三个内角.
的单位球面上有不同在一个大圆上的三点
.
(1)球面
的三条边长相等(称为等边球面三角形),若
,求球面
的内角和;
(2)类比二面角,我们称从点
出发的三条射线
组成的图形为三面角,记为
.
其中点
称为三面角的顶点,
称为它的棱,
称为它的面角. 若三面角
的三个面角的余弦值分别为
.
(ⅰ)求球面
的三个内角的余弦值;
(ⅱ)求球面
的面积.
![](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/16d65cecaf8a3dc2953f4109c75a981e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/667349d99185bb045030b733352ff7fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdcdeb8eb2d5a8a7f1c81071ae349504.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f2dcc2105ebb1c89bfb1572a7e076e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a19c1bcb8431ae315ecd29c6478d3eff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ef528373d472534670a8fd7fb301492.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a1b98b1478ed9480a9e1a62ec3b82da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e037d52e5d75070cd02df4727b5922d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
(1)球面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c814dc3914cdf4d5af2f4cfadf41c260.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)类比二面角,我们称从点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f673831a6738e1c317fede2920436d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5de938433cfaf25cb38dd5c9d915bb2b.png)
其中点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f673831a6738e1c317fede2920436d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04c93fa5e252ef36adfbffa39410f2b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4278c0911e7df78965e78cff69cac5f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27029c4cc0fe55c8f4dbdb33beca9980.png)
(ⅰ)求球面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(ⅱ)求球面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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