如图,在
中,
,D为
的中点,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/2/4839cdc4-f694-4c28-9cee-ac196c238416.png?resizew=189)
(1)求证:四边形
是菱形;
(2)连接
,若
,
是等边三角形,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b3bcd66e0bc4c6d2eb2804635ae6ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7045b628830dcb470dabb5b14e54907a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/2/4839cdc4-f694-4c28-9cee-ac196c238416.png?resizew=189)
(1)求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8bc1cbcd6d00f0c36bad8254297d9f33.png)
(2)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e1f4f255d191786f7d330d278868c2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
更新时间:2023-04-26 08:47:00
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【推荐1】已知:如图,在等边三角形ABC的AC边上取中点D,BC的延长线上取一点E,使BD=DE.求证:CD=CE.
![](https://img.xkw.com/dksih/QBM/2019/2/8/2136056104607744/2137976687288320/STEM/c0ca346f3173497f8f1a86bad2fa5e71.png?resizew=144)
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【推荐2】如图,在等边△ABC中,P为BC上一点,D为AC上一点,且∠APD=60°,BP=1
,CD=
,求△ABC的边长.
![](https://img.xkw.com/dksih/QBM/2018/3/28/1912011749122048/1916602789011456/STEM/398fe177ff8d49f38c016d2a78cca2d2.png?resizew=5)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
![](https://img.xkw.com/dksih/QBM/2018/3/28/1912011749122048/1916602789011456/STEM/d4e505deab7d44da92dd81db2106bf33.png?resizew=144)
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【推荐1】综合与实践:
(1)问题发现:如图1,
和
均为等边三角形,点A,D,E在同一直线上,连接![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bd97740e8f35c9c05f8bb53c0f1cb47.png)
的度数为______;(直接写出)
②线段
之间的数量关系为______(直接写出)
(2)类比探究:如图2,
和
均为等腰直角三角形,
,点A,D,E在同一直线上,
为
中
边上的高,连接![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bd97740e8f35c9c05f8bb53c0f1cb47.png)
①
的度数为______;(直接写出)
②证明:线段
之间的数量关系;(详细过程)
(3)拓展延伸:在(2)的条件下,若
,求四边形
的面积.(详细过程)
(1)问题发现:如图1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90b40c2b0ab8e1cfe5112d428b4b829f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a0acc93490a6a784eb62201d93dd93d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bd97740e8f35c9c05f8bb53c0f1cb47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a55a1a244f81097e05e715b69580faa.png)
②线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6b0a3fa475b24f57ecd79c681259561.png)
(2)类比探究:如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90b40c2b0ab8e1cfe5112d428b4b829f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a0acc93490a6a784eb62201d93dd93d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fc75953bf5dcfa4af308c34bf9952d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db54223bb3fc2fe2497213a4d1f94827.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a0acc93490a6a784eb62201d93dd93d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bd97740e8f35c9c05f8bb53c0f1cb47.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a55a1a244f81097e05e715b69580faa.png)
②证明:线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ef40df25159eb0d39c7d0219c5219cb.png)
(3)拓展延伸:在(2)的条件下,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c6692c94773a35addead41fb0e4922d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42a876bc003f6c042c24ff4d8c11c8a8.png)
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【推荐2】如图1,在等腰
中,
,分别延长AO、BO至点C、点D,使得
、
,连接AD、BC.
如图1,求证:
;
如图2,分别取边AD、CO、BO的中点E、F、H,猜想
的形状,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50709a24d5d8394fa24a6d3e3610e642.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c9cf153e2840e2523e31ffea2b5a1ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/17b3cd28fe1a1411f59a0466e2e0e621.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d3f9fa5aa1cd4430679e51f047d5432.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9bf6c84731e5e1bd335ecfc2d36c3d81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04869322569c65c645665c74417fb4a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f53190d6ead827a6338b9de847aeaf1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4360393b83e6155442e2de6c8d6debda.png)
![](https://img.xkw.com/dksih/QBM/2019/3/28/2170148174340096/2171043765649408/STEM/f94fc11541674d3d98c099967664d697.png?resizew=395)
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解答题-作图题
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【推荐1】如图,已知矩形
.
,使点
分别在
边上,(不写作法,保留作图痕迹,并给出证明.)
(2)若
,求菱形
的周长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2330c01a4d2b5b20f106e3e48834d5c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cf9b288c48c73463a2f214f02b6952a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ba48366317ebea1c9dd5e4e67e03092.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b38f706346203b0c213fa3b33f2f28d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2330c01a4d2b5b20f106e3e48834d5c0.png)
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【推荐2】如图1,将一张矩形纸片
沿直线
折叠,使点C落在点A处,点D落在点E处,直线
交
于点M,交
于点N.
,则
__________
;
(2)如图2,连接
.求证:四边形
为菱形;
(3)若
的面积与
的面积比为
,
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](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/e968e7dd2238a8343fc319f156ce94bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f96837eba7dea6cf965bd8db060ccd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
(2)如图2,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167d31eb8432b5c0364316e5048c23dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b977f9880c3acc912c36aa3e2df56c9.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98013a5042685a1db94249e70c62c09a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a5e0a51c9e14fb246b0ba0b231c1e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84783b6ba0f36789519816101a437f46.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06fa0a286a55692e4263a5993b01580b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
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【推荐1】如图,等腰
,
,将
沿
翻折至
,延长
交
于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/17/89ab93c3-c1c2-4bd4-bc58-7c7180aa0171.png?resizew=142)
(1)求证:
;
(2)若
是直角三角形时,探索线段
与
的数量关系.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67d822262ff00915910e5b87d81ad1ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/17/89ab93c3-c1c2-4bd4-bc58-7c7180aa0171.png?resizew=142)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bf72e6e991d6bb30b02e7ca57fc92f2.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80651f797ab9dccfd7163c605b091ad5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
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【推荐2】如图,在△ACE中,CA=CE,∠CAE=30°,⊙O经过点C,且圆的直径AB在线段AE上.
(2)若△ACE中AE边上的高为h,试用含h的代数式表示⊙O的直径AB;
(3)设点D是线段AC上任意一点(不含端点),连接OD,当
CD+OD的最小值为6时,求⊙O的直径AB的长.
(2)若△ACE中AE边上的高为h,试用含h的代数式表示⊙O的直径AB;
(3)设点D是线段AC上任意一点(不含端点),连接OD,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
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【推荐3】我校九年级“卓越数学”兴趣小组,“双减”之后,开展多项减负提质实践课,周末他们用所学到的知识测量附近一幢楼房的高度,由于到楼房底部的水平距离被建筑护坡遮挡,不易测量,他们通过实地观察、分析,制订了可行的方案,并进行了实地测量.已知楼房AB前有一斜坡CD,它的坡度
.他们先在坡面D处测量楼房顶部A的仰角
,接着沿坡面向下走到坡脚C处,然后向楼房的方向继续行走至E处,再次测量楼房顶部A的仰角
,并测量了C、E之间的距离,最后测量了坡面C、D之间的距离.为了减少测量误差,小组在测量仰角以及距离时,都分别测量了两次并取它们的平均值作为测量结果(测角仪高度忽略不计),如下表:
(1)任务一:两次测量C,D之间的距离的平均值是______米;
(2)任务二:请你帮助“卓越数学”小组根据上表中的测量数据,求出该楼房AB的高.(结果精确到0.1米.参考数据:
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df98c7b41e565f2f1f0b36fb98cfe3bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080e6068fddddcfbe74687b4d015188d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a55a1a244f81097e05e715b69580faa.png)
项目 | 内容 | ||||
课题 | 测量学校附近楼房的高度 | ||||
测量示意图 | ![]() | 说明:测点D、E与点C、B都在同一水平面上 | |||
测量数据 | 测量项目 | 第一次 | 第二次 | 平均值 | |
仰角∠ADM的度数 | 30.1° | 29.9° | 30° | ||
仰角![]() | 59.9° | 60.1° | 60° | ||
C、E之间的距离 | 5.1米 | 4.9米 | 5米 | ||
C、D之间的距离 | 11.8米 | 12.2米 | ? | ||
… | … |
(2)任务二:请你帮助“卓越数学”小组根据上表中的测量数据,求出该楼房AB的高.(结果精确到0.1米.参考数据:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df276e9b9424486d59c747f1227b213c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/721554f715d299b5e1974e58aae90897.png)
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