1 . 工兵用信号探测器探测边长为2千米的等边三角形区域内的地雷,已知探测器的有效作业距离为
千米,从三角形的一个顶点出发,工兵至少需要行走多少距离才能完成探测任务?(要求说明理由)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62a711b601b52e4116fc5e8e7d2949e1.png)
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2 . 如图,已知
、
、
、
四点共圆,四边形
是平行四边形,
是
与
的交点,
.证明:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bcaadfa991b0edf9163751f42d39b54.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60dc9f8e47e78b7f4ab2dd9cd559f601.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0914b68f106a912420705b2f3928ca42.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce1132157a33c82610c2d5035493d024.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/289d7a880379d6060065c829b45b0ed6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/655b6a742dbacdab5aaa298007663dd4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9005a613eaecad3406f9818fb278357c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bcaadfa991b0edf9163751f42d39b54.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/25/434c7151-f90e-4ae0-ba47-2a6ccd55c11c.png?resizew=205)
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3 . 设
为正整数,
,
,令![](https://staticzujuan.xkw.com/quesimg/Upload/formula/649309617a29d1b9d4b2373d3c1c2946.png)
.求证:存在
使得
,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4887473a8091e1ef53a169cc9f211e3a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e65369cec2aac72a87c314f4c7ba143.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0be022d2478bb5f67d3e98f1319ea821.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/649309617a29d1b9d4b2373d3c1c2946.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/264d2ca5912fe1d6c354d7b0fd5efe4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00a28be4d5a16cf245f6fa7c4088fee4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0f7741f4975d9df3daa0c1cdd23c9df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/264d2ca5912fe1d6c354d7b0fd5efe4f.png)
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4 . 已知
、
、
都是正数,且
.
求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e81e59019989b7dc2fb59b037ef6e010.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff87256fdc337d698e6a9b9ebb48ea51.png)
求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d19dd46c292deb2b5113f9012b760ee.png)
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