某农户准备建一个水平放置的直四棱柱形储水器(如图),其中直四棱柱的高
,两底面
是高为
,面积为
的等腰梯形,且
,若储水窖顶盖每平方米的造价为100元,侧面每平方米的造价为400元,底部每平方米的造价为500元.
![](https://img.xkw.com/dksih/QBM/2017/10/4/1788204906749952/1790014480867328/STEM/ccc07059b41d434ab4bc10f7193220d2.png?resizew=161)
![](https://img.xkw.com/dksih/QBM/2017/10/4/1788204906749952/1790014480867328/STEM/05797664bfbf4fe2978e2fd0cf20349a.png?resizew=203)
(1)试将储水窖的造价
表示为
的函数;
(2)该农户如何设计储水窖,才能使得储水窖的造价最低,最低造价是多少元?(取
).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6b0c69c78aa10e3742caeba770dbd37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fad491e5b5e14c49ef8b7004ebcfcef9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0b45b8e2e110dd02163002af2e3dea2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f162f13dbbc8ca61d3dc42a32b132b00.png)
![](https://img.xkw.com/dksih/QBM/2017/10/4/1788204906749952/1790014480867328/STEM/ccc07059b41d434ab4bc10f7193220d2.png?resizew=161)
![](https://img.xkw.com/dksih/QBM/2017/10/4/1788204906749952/1790014480867328/STEM/05797664bfbf4fe2978e2fd0cf20349a.png?resizew=203)
(1)试将储水窖的造价
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
(2)该农户如何设计储水窖,才能使得储水窖的造价最低,最低造价是多少元?(取
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/833feab71a2184edffcacd5234a50132.png)
更新时间:2017-10-07 10:16:41
|
【知识点】 用料最省问题
相似题推荐
解答题-问答题
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适中
(0.65)
名校
【推荐1】一根长为
的铁棒
欲水平通过如图所示的走廊(假定通过时贴着内侧的圆弧墙壁,如图),该走廊由宽度为
的平行部分和一个半径为
的四分之一圆弧转角部分(弧
段,圆心为
)组成.
![](https://img.xkw.com/dksih/QBM/2020/11/23/2599219953795072/2599915910225920/STEM/6d1749c8-e1b9-4a08-a71b-70c63de3fc6e.png?resizew=216)
(1)设
,试将
表示为
的函数;
(2)求
的最小值,并说明此最小值的实际意义.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acf977507957c4775a5abd2e51c0c8df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c97599b586b7decae67a55cd008b9091.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://img.xkw.com/dksih/QBM/2020/11/23/2599219953795072/2599915910225920/STEM/6d1749c8-e1b9-4a08-a71b-70c63de3fc6e.png?resizew=216)
(1)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c6bba53ad8d6862996fcc14811d0306.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
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适中
(0.65)
解题方法
【推荐2】某景区准备设计一景观,其上部是圆锥形的顶棚,如图所示.圆锥顶点为B,底面圆心为O,半径为2米.通过金属杆AB支撑在地面A处(AB垂直于地面),
,
,…,
支撑着顶棚,
,
,
,…,
是底面圆周上的n等分点,圆锥顶点距地面10米,设金属杆
,
,…,
所在直线与圆锥底面所成的角都为
(金属杆不计粗细).
![](https://img.xkw.com/dksih/QBM/2021/11/28/2865890005508096/2927430817816576/STEM/e9d42eaf-85a3-4cc0-86a2-df2aeebd8e92.png?resizew=173)
(1)当
为60°且n=3时,求AO,
,
,
的总长.
(2)当n一定,
变化时,为美观与安全起见,要求AO,
,
,…,
的总长最短,此时
的正弦值是多少?并由此说明n越大,O点的位置将会上移还是下移.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9460e8571262302490aca08902d67c4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4b6c03a586ca49ad576c3a2cb0f6d67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4372cf0278c3da74bb6313b704cd8c22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e67927616b141ed7c6b83f8b6f4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf83e20035c3afd6d26ebfd53d768a70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9460e8571262302490aca08902d67c4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4b6c03a586ca49ad576c3a2cb0f6d67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4372cf0278c3da74bb6313b704cd8c22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://img.xkw.com/dksih/QBM/2021/11/28/2865890005508096/2927430817816576/STEM/e9d42eaf-85a3-4cc0-86a2-df2aeebd8e92.png?resizew=173)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9460e8571262302490aca08902d67c4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4b6c03a586ca49ad576c3a2cb0f6d67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a01a93934db9637eeee23bac1c41c58.png)
(2)当n一定,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9460e8571262302490aca08902d67c4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4b6c03a586ca49ad576c3a2cb0f6d67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4372cf0278c3da74bb6313b704cd8c22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
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