解题方法
1 . 在
中,
,则cosA=_______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfc99288b84205501fb37a16e9b32a51.png)
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2 . 在
中,角A,B,C的对边长分别为a,b,c,若
,
,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ccd4162c7d09f970cb77cadacdbe521.png)
_________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65397f11ea8af736f38debadf420c4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15ee608882881caff2f1e223177424ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/905f306dc08525842a96cfcab32c1ce8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ccd4162c7d09f970cb77cadacdbe521.png)
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解题方法
3 . 已知
,且
是第一象限角,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d292bf76cce13b6557add93f6661329.png)
__________________ ..
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/161b0fd0f17495d65823299e0476dd15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d292bf76cce13b6557add93f6661329.png)
您最近一年使用:0次