已知矩形纸片
中,
,将矩形纸片的右下角沿线段
折叠,使矩形的顶点B落在矩形的边
上,记该点为E,且折痕
的两端点M,N分别在边
上.设
,
的面积为S.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/f900c1b9-ec1d-4e87-a85f-43b874945ccd.png?resizew=103)
(1)将l表示成θ的函数,并确定θ的取值范围;
(2)求l的最小值及此时
的值;
(3)问当θ为何值时,
的面积S取得最小值?并求出这个最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1395afe863a562ba4a247ac5f938398.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/374fe9986ebbc986fc422e514ab93a51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95b91ff96bdd184bf8683aa62d0ea207.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b71393e295afec37421cfa3bd0583905.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/f900c1b9-ec1d-4e87-a85f-43b874945ccd.png?resizew=103)
(1)将l表示成θ的函数,并确定θ的取值范围;
(2)求l的最小值及此时
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de7d5ef3a3d9a03be91135fc426d57cc.png)
(3)问当θ为何值时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b71393e295afec37421cfa3bd0583905.png)
更新时间:2020-03-25 19:33:51
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【推荐1】从今年起,我国将于每年5月第四周开展“全国城市生活垃圾分类宣传周”活动,首届全国城市生活垃圾分类宣传周时间为2023年5月22日至28日,宣传主题为“让垃圾分类成为新时尚”,在此宣传周期间,某社区举行了一次生活垃圾分类知识比赛.要求每个家庭派出一名代表参赛,每位参赛者需测试A,B,C三个项目,三个测试项目相互不受影响.
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(1)若某居民甲在测试过程中,第一项测试是等可能的从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(2)现规定:三个项目全部通过获得一等奖,只通过两项获得二等奖,只通过一项获得三等奖,三项都没有通过不获奖.已知居民乙选择
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0cc6293cfedec30b124ece908c4c438.png)
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【推荐2】已知函数
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(3)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ecc70df44c7dae5330a2dcdb8a690cc.png)
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【推荐3】已知函数
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51c530f4b7491b95acb8ce3eef9aa09d.png)
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(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d303c3cf355771c23e93a6a0ff9c618.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c2ada6241afa216856e04a211ecb272.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e84303f011517f34a84eb48de7afef75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
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【推荐1】如图,以坐标原点O为圆心的单位圆与x轴正半轴相交于点A,点B,P在单位圆上,且![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0efead1d0e9b5d832b8217739fbed13e.png)
![](https://img.xkw.com/dksih/QBM/2018/6/1/1957812978368512/2021430658088960/STEM/b56595a3b1104254ad1118da6f9aeca8.png?resizew=153)
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