1 . 某地有四家工厂,分别位于矩形ABCD的四个顶点.已知
,
.为了处理这四家工厂的污水,当地政府打算在该矩形区域上(含边界)建造一个污水处理厂O,并铺设一些管道连通各家工厂和污水处理厂.记需要铺设管道的总长度为L(单位:km).现有以下两种建设方案.
(1)第一种方案计划将污水处理厂建在矩形区域内部,并在各家工厂与污水处理厂之间用管道直接连通.求该方案下L的最小值;
(2)第二种方案计划将污水处理厂O建在对角线 AC、BD 的交点处,并在矩形区域内部选择两个关于 O 对称的点P、Q作为管道的分叉点,试确定该方案下L取得最小值时,分叉点P、Q的位置.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67dbd5e668ac696bdf1bc7e4e4babc00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cf1ebaf51acdd9c790c17053cffb7d0.png)
(1)第一种方案计划将污水处理厂建在矩形区域内部,并在各家工厂与污水处理厂之间用管道直接连通.求该方案下L的最小值;
(2)第二种方案计划将污水处理厂O建在对角线 AC、BD 的交点处,并在矩形区域内部选择两个关于 O 对称的点P、Q作为管道的分叉点,试确定该方案下L取得最小值时,分叉点P、Q的位置.
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解题方法
2 . 在平面上,已知
为两个不平行的单位向量,O为定点,集合
,若
中所有的点构成图形的面积为1,则
与
夹角的大小为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f9c91af174ebe66c921f52db385a6c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa290b89f748483f9b959b17200a001e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0047f659c182291c84c224df6b5e993f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a2f4b1178f68bd147d1a2a6acd04435.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c94075193c11fe43f2396cff5a485054.png)
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名校
3 . 在锐角
中,
,
为边
上的点,
与
的面积分别为2和4,过
作
于
,
于
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2f12fabee2398bdd3d27b90f82778d2.png)
_________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e85b8eb4f3e02fa8ab3b49def8958444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db5e1441a49e782ff0ef46e776cde06a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9f8f01137e92c0f2e63467036ae9cce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32c38dfd14dde969702dff97ef2270f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/761a77e11e1e45c2a8b2d34d22cf8e04.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2f12fabee2398bdd3d27b90f82778d2.png)
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名校
4 . 在
中,
,
,且
,设
为平面
上的一点,则
的最小值是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f08273d339dc5ddbb89aa67bb8205e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8a7b5adfcac0f46a4cd19da4ebb4a2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cffb420852763fc7af5b82ff48e753b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6dd94c5bd4d1a01ca106a02628ee4cc0.png)
A.1 | B.![]() | C.-7 | D.![]() |
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5 . 如图所示,在直角
中有一内接正方形
,它的一条边
在直角
的斜边
上,设![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3efd363abedb20d3c8d395e7ed11c681.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/603cacbe-5162-4232-8cba-15e0366989d7.png?resizew=189)
(1)用
和
表示出
的面积
和正方形
的面积
;
(2)当
变化时,求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2257da1e2425f2ea9ac7440f52659ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3efd363abedb20d3c8d395e7ed11c681.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/603cacbe-5162-4232-8cba-15e0366989d7.png?resizew=189)
(1)用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2257da1e2425f2ea9ac7440f52659ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c92cd169360ffdb827d40f3dbc7c7ad1.png)
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6 . 如图,在
中,已知AB=5,BC=8,AC=7,动点P、Q分别在边AB、AC上,使
的外接圆与BC相切,则线段PQ长的最小值为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecc3919b5000f9af77ddb77a62bee9c9.png)
![](https://img.xkw.com/dksih/QBM/2018/12/19/2100144453959680/2105644056477696/STEM/d141a86a-ace6-49ca-acff-c46eeccb3971.png?resizew=259)
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7 . 如图,在等腰
中,
,
为斜边
上的一动点,联结
,作
,垂足为
.求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfa8cee7d2463f6f7d352e8b65f47cf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b937442ad4cc480adc11bb143559454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fd5643cc087924a1e3f7ae948f88882.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/17/d4d69dca-5c4d-449e-b9d7-f99b10c77335.png?resizew=120)
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8 . 设
是单位圆
的一条弦.若
的面积恰好等于以
为边的正方形的面积,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a2979f64c85f82d8975d73ee1c342de.png)
______ (精确到0.001度).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a2979f64c85f82d8975d73ee1c342de.png)
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9 . 如图,已知
是正方形
的边
所在的直线上的一动点. 求
的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3d7e6d4149b9eda735e01e486f591b8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/7/14ebc8b9-aea7-4dc6-b1f0-fff424d35af3.png?resizew=121)
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10 . 设
分别为凸四边形
的边
的中点,且
.则
和
之间的夹角为______ (精确到
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cab0ed07775b0fdcb368b696a0f65422.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b589ca985b32e60ea2e39fe58d4ac9d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a63b5f2a0ce1c9c9811f20326b9b918.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e55e398e8520d8a36fb5a625a085b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c83f1f880e5ffbff036953acaca90c41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2736189910123acbc48d7c58b03f5659.png)
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