解题方法
1 . 数学课上,老师出示了以下习题:已知圆柱内接于半径为3的球
,求圆柱体积
的最大值.为了求出圆柱体积
的最大值,小明和小亮两位同学分别给出了如下两种方案:
(1)小明的方案:设圆柱的高为
,请你帮他写出体积
与
之间的函数关系式,并求出圆柱体积的最大值;
(2)小亮的方案:取圆柱底面圆
上一点
,连接
,
,设
,请你帮他写出体积
与
之间的函数关系式,并求出圆柱体积的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
(1)小明的方案:设圆柱的高为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)小亮的方案:取圆柱底面圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12fe32dfbd66709875c5b9f79c9496da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef49a3ca580a144cc65a609c167facc1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f78322f1db1b2e332225b9db53b9c54a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c2b16d0606a8f07d62da5b3fcf55a03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
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