1 . 如图,已知线段a和b,直线AB和CD相交于点O,∠COB=90°,利用尺规,按下列要求作图:
![](https://img.xkw.com/dksih/QBM/2016/3/18/1574184299642880/1574184305434624/STEM/a0d13087619948fe88163ebc1b531bae.png)
(1)在射线OC,OD上分别作线段OE,OF,使它们分别与线段a相等,在射线OA,OB上分别作线段OG,OH,使它们分别与线段b相等;
(2)分别连接线段EG,GF,FH,HE,你得到了一个怎样的图形?
(3)点G与点H之间的所有连线中,哪条最短?请说明理由.
![](https://img.xkw.com/dksih/QBM/2016/3/18/1574184299642880/1574184305434624/STEM/a0d13087619948fe88163ebc1b531bae.png)
(1)在射线OC,OD上分别作线段OE,OF,使它们分别与线段a相等,在射线OA,OB上分别作线段OG,OH,使它们分别与线段b相等;
(2)分别连接线段EG,GF,FH,HE,你得到了一个怎样的图形?
(3)点G与点H之间的所有连线中,哪条最短?请说明理由.
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2 . (1)问题背景
如图1,P为
内部一点,连接
,将
绕,点C顺时针旋转
得到
,连接
,
,
,可知
为___________三角形,故
,又
,故
,由___________可知,当
在同一条直线上时,
取最小值,如图2,最小值为
,此时的P点为该三角形的“费马点”.
(2)问题解决
如图3,在
中,三个内角均小于
,且
,
,
,求
的最小值;
(3)问题应用
如图4,设村庄
的连线构成一个三角形,且
,
,
.现欲在
内部建一中转站P沿直线向
三个村庄铺设电缆,已知由中转站P到村庄
的铺设成本分别为
元
,
元
,
万元
,是否存在合适的P的位置,可以使总的铺设成本最低,若存在请求出成本的最小值.
如图1,P为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ef613539d5e569f11d33c1f46d03120.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9524e3810e06dc781285f1289e75d653.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19736af03116d7cf8b1ebaeda148b63d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a99e1ad0d6fb0f13be56d09086366c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bd317bbea3d695c02357c7ebcfa70c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dafcd7c0c071987b92079243f355891.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e859a0e6d38eaf05756f1012d561062.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc0a40248b2d601aa33d94cdc3cf7d90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33b5cf040dbc5948fbe1bc3cde813dd4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db7fbf7c895ac2ed5bfa19627bbcfdcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1336922d3354875d556b10c684a9085e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7ed53a398b1d6b7b4abbb43a9abcf1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e663220a66eff19da6a71e46b397db2e.png)
(2)问题解决
如图3,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d70dc2c20619a4fc12a0cfda59af5b69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/392b9e1a179a6676362679354a9e7e51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7ed53a398b1d6b7b4abbb43a9abcf1f.png)
(3)问题应用
如图4,设村庄
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff76846660a607dae65b956967b4c2f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31fe51e912e65edc42a8157c37789b06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8606542896b8b6e110c963218e4d76d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/392b9e1a179a6676362679354a9e7e51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff76846660a607dae65b956967b4c2f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff76846660a607dae65b956967b4c2f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dadc63e6e33743ce590ed968948a5a58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a98024ce2e23a5e81b2bcdd7c96ccef9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dadc63e6e33743ce590ed968948a5a58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a98024ce2e23a5e81b2bcdd7c96ccef9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b1b8bd4a2d822a44598ca977ca7355a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a98024ce2e23a5e81b2bcdd7c96ccef9.png)
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3 . (1)如图1,在平面直角坐标系中,点
的坐标分别为
,现同时将点
分别向上平移2个单位,再向右平移1个单位,分别得到点
的对应点
,连接
,
,直接写出点
的坐标______,
的坐标______及四边形
的面积为______.
(2)如图2,A,B两单位分别位于一条封闭街道的两旁(直线
是街道两边沿),现准备修建一座过街人行天桥.天桥应建在何处才能使由A经过天桥走到
的路程最短?在图3中作出此时天桥
的位置,简要叙述作法并保留作图痕迹(注:桥的宽度忽略不计,桥必须与街道垂直).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e52586ca2a3b783bc8092415e2d4bf6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fae6b06d711c3a0b795cb209b6df64db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e52586ca2a3b783bc8092415e2d4bf6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39acab3cfb59bfc9591371721ab01d93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0eb0c11e4b7aa9030a6691aee35eed0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(2)如图2,A,B两单位分别位于一条封闭街道的两旁(直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44434b647ec546fe787e2164e0be6cd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
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名校
4 . 如图,在边长为
的正方形
中,点
在
边上,且
,点
是
边上的动点,连接
,以
为直角边,以
为直角作如图所示的等腰
,则当
最小时
的长为___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3304e23f3b0f9569c4140ca89b6498.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.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/60634341a9603e24b2bbc6960abe3d31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a298ed3325baafd125f688496fd52e8e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daae059ba37e6fa23de549fb4db6d3e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21737ff1c390544b015d5295c568de4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
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