如图,AD为△ABC的中线,BE为△ABD的中线.
(1)用圆规和无刻度的直尺在△BED中作BD边上的高EF;
(2)若△ABC的面积为40,BD=5,求EF的长.
(1)用圆规和无刻度的直尺在△BED中作BD边上的高EF;
(2)若△ABC的面积为40,BD=5,求EF的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/2/24565a08-91c7-43b4-8d85-9d73c0b3bedc.png?resizew=181)
更新时间:2016-12-06 11:56:50
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相似题推荐
解答题-证明题
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【推荐1】如图1,AM为△ABC的BC边的中线,点P为AM上一点,连接PB.
(1)若P为线段AM的中点.
①设△ABP的面积为S1,△ABC的面积为S,求
的值;
②已知AB=5,AC=3,设AP=x,求x的取值范围.
(2)如图2,若AC=BP,求证:∠BPM=∠CAM.
(1)若P为线段AM的中点.
①设△ABP的面积为S1,△ABC的面积为S,求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d000f3b4aa8785c2811633366cec280.png)
②已知AB=5,AC=3,设AP=x,求x的取值范围.
(2)如图2,若AC=BP,求证:∠BPM=∠CAM.
![](https://img.xkw.com/dksih/QBM/2022/1/5/2887713242374144/2887796000104448/STEM/d1dcf814-8350-4199-a4b5-4de5e95bf0b3.png?resizew=420)
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【推荐2】如图,在
中,
,
是
上一点,且
.
![](https://img.xkw.com/dksih/QBM/2020/7/22/2511611845435392/2512145824120832/STEM/5c9a3ef852cf4f5f8674d0567e72f6a2.png?resizew=520)
(1)求证:
.
证明:在
中,
∵
(已知)
∴
( )
又∵
(已知)
∴
(等量代换)
∴
( )
(2)如图②,若
的平分线分别交
,
于点
,求证:
.
(3)如图③,若
为
上一点,
交
于点
,
,
,
.
①求
的值;
②四边形
的面积是 .
![](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/dcd6fe78f6cfdfefd6d8be45473b25b9.png)
![](https://img.xkw.com/dksih/QBM/2020/7/22/2511611845435392/2512145824120832/STEM/5c9a3ef852cf4f5f8674d0567e72f6a2.png?resizew=520)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b757f0c42ae5c9a2d6a4b19e5877b27.png)
证明:在
![](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/225c56a2c4e5d00893595b161b9b5481.png)
又∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcd6fe78f6cfdfefd6d8be45473b25b9.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60a273b81b5b386f4d6da3243535de43.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4795ee1f96b430529934e2231b38885d.png)
(2)如图②,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbce11aa19b8bd2bf6ee5a834e005de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d70de1ffdd9aa376b09bbcfa12644a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe1b65f6ef0f3b7ed731a277f9d10f7c.png)
(3)如图③,若
![](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/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bdf2a5cee6ec964fb861813805d06fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c5901056b42a05c68f472d826775a82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f837ae9e60ed77471cf28840163569c.png)
①求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43c3bd317daaa5231fd738c7f0971fc7.png)
②四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ac66de8543430fd51e7c18042e626dd.png)
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解答题-证明题
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【推荐3】小孙和小悟同学在探究四边形
内作一条直线将它分成面积相等的两部分时,遇到了困难,于是两位同学想到了先从三角形研究起.
(1)如图1,
是
的中线,试判断:
_________
(请填 “
”、“
”或“
”);
(2)如图2,
,试判断:
_________
(请填“
”、“
”或“
”);
【深入思考】有了这样思考问题的经历,于是小孙同学对探究四边形
内作一条直线将它分成面积相等的两部分给出一种思路:如图3,小孙同学的辅助线:①连接对角线
,②作
交
的延长线于
;③取
的中点
,则直线
为所求直线.小孙同学还尝试从理论上给予说明,请你帮助将说理过程补充完整:
∵
,
∴
_________(由问题2的结论得)
∴
_________,
即
_________,
∵
是
的中点,
∴
_________(由问题1的结论得)
∴
平分
的面积,即
平分四边形
的面积.
和
;②取
的中点
,③连接
、
;④过点
作
的平行线与四边形
的边
交点于
,则直线
则为所求直线.
请你独立尝试完成小悟同学的说理过程.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(1)如图1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4673ef63a8d89687b96ee09887ac3daa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5c141b06b158e0cdef08fcda3ea44a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/392cdb9d30684cce244bef94b8d861b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ff7942da6c3fc4005256fb1458557c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
(2)如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4adf90a8c2b29334cdc5aa5b554991f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5cbff84327e964f912a54032e76ccc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b04d3d8f7186477d8bb752a7ac56b1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/392cdb9d30684cce244bef94b8d861b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ff7942da6c3fc4005256fb1458557c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
【深入思考】有了这样思考问题的经历,于是小孙同学对探究四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/105068b25f5a63af32f4082cfe08691e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95cc39bd5f811ee710c8a9fb73d57791.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b53a05334b35ffb5c7d94189e8e5b62a.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3ce2aea3ff8ec24e31b437ae59a35d3.png)
即
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32995b3d5327ca12ed93c5bd41678a4a.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b38d321858fb90c33f87f12554bcac6e.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e742966e3711cfa53dce04022acf4bcc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
请你独立尝试完成小悟同学的说理过程.
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解答题-作图题
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名校
【推荐1】如图,已知□
.
(1)作出
的垂直平分线,交
于点
,交
于点
,(用尺规作图,保留作图痕迹,不要求写作法);
(2)在(1)的条件下,连接
,
,若
,
,求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(1)作出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.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/a0ed1ec316bc54c37c4286c208f55667.png)
(2)在(1)的条件下,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98bd4952d7c7a7ba4a015dc69814361a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ace6f0f73bd65c82e681e06d7c78c4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b55b502f406c3525ce81b60bdfdc11e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/5/916162aa-9bc6-434d-816d-247559577bf4.png?resizew=175)
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解答题-作图题
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【推荐2】已知矩形ABCD,请用尺规在矩形ABCD中作出一个面积最大的菱形,并标注必要的字母及结论(保留作图痕迹,不要求写作法)
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解答题-作图题
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名校
【推荐3】下面是某数学兴趣小组探究用不同方法作一条线段的垂直平分线的讨论片段,请仔细阅读,并完成相应任务。
任务:
(1)小文得出点
在线段
的垂直平分线上的依据是________________________;
(2)小明作图得到的直线
是线段
的垂直平分线吗?请判断并说明理由:
(3)如图3,已知
,
,
,点
,
分别为射线
,
上的动点,且
,连接
,
,交点为
,当
时,请直接写出线段
的长.
小文:如图1,(1)分别以![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() 由作图可知, ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() 小明:我认为小文的作图方法很有创意,但是可以改进如下,如图2,(1)分别以 ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
(1)小文得出点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
(2)小明作图得到的直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
(3)如图3,已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcca02c57f5859f49f91d445b4a06d52.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63e4d19bf237a6fca67e0d01a9ddb726.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/305a88d4e0249bd16d48eda01331d2d4.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/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ed66431681da1db8f7cb0f40cd19201.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
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