1 . 已知实数
,
,
.
(1)若
,求
的值;
(2)求证:
;
(3)用反证法证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce613eaa5df46a50174085ef5d1087fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/751e274e9107d780c39ba9c49d6daefb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1f9223bc24df8d429d743692fff7c06.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/919f4bbc4dd7aef5314ac0e183872d6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9f2416d1f75a45a314331146550832e.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09b469b34530be2e760b144b8a571506.png)
(3)用反证法证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f75807858b7804a1ad2039c41f323a18.png)
您最近一年使用:0次
2 . 已知
.
(1)若
,
,证明
为锐角三角形;
(2)如图,过顶点
作
,垂足
位于边
上.若
且
,证明
不是直角.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a32841dea3e0f06078e09450d29dbfac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/994eeb7944c572291623825627af7ea2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)如图,过顶点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b757f0c42ae5c9a2d6a4b19e5877b27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bacfdde1c91d4404be2fdf515a03437d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55c24a968c73e960698a572ab01e3698.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fabb884dc5f9609de491245463bbe9a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/15/f9272433-89e2-4fe7-9df7-e62ab88224ad.png?resizew=168)
您最近一年使用:0次