名校
解题方法
1 . 仙桃中学新校区有一近似矩形的水塘
,已知长
米,宽
米,为了便于师生平时休闲锻炼,学校计划在水塘建造三座小桥
和
,并要求
是
的中点,点
在边
上,点
在边
上,且
为直角,如图所示.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/4/e921e78a-ab68-45b1-a01e-0b8278b82c07.png?resizew=273)
(1)设
(弧度),试将三座桥的全长(即
的周长)
表示成
的函数,并求出此函数的定义域;
(2)建这三座桥,每米建设预算平均费用为1250元,试问如何设计才能使总费用最低?并求出最低总费用(结果保留整数)(可能用到的参考值:
取
取1.42).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3dd4997da49b3dfe98144ad13aed0d5c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e3ad33a186a955f03484e061dc646ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb4c8c61a1d2919aba41ed3021d3a053.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bb9fc77f75349c3463fea7effa4e225.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/4/e921e78a-ab68-45b1-a01e-0b8278b82c07.png?resizew=273)
(1)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d49a5353792a94188f336831cfad0f5d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd35bd406de97d29594aff377b213fac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
(2)建这三座桥,每米建设预算平均费用为1250元,试问如何设计才能使总费用最低?并求出最低总费用(结果保留整数)(可能用到的参考值:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2fbe3d71af16d0925975d1699824cc7a.png)
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