在平行四边形ABCD中,过点D作DE⊥AB于点E,点F在边CD上,DF=BE,连接AF,BF.
(1)求证:四边形BFDE是矩形;
(2)若CF=6,tanC=
,DC=16,求证:AF平分∠DAB.
(1)求证:四边形BFDE是矩形;
(2)若CF=6,tanC=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d599cb4a589f90b0205f24c2e1fa021e.png)
![](https://img.xkw.com/dksih/QBM/2020/8/17/2529557192941568/2530533461745664/STEM/bace02e8bf8745bca7d6bf381e098d41.png?resizew=189)
更新时间:2020-08-18 16:06:25
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解答题-证明题
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【推荐1】如图,在▱ABCD中,点E为CD的中点,连接BE并延长交AD的延长线于点F.求证:点E是BF的中点,点D是AF的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/17/9bfb6047-bf1c-4ee3-b239-faf0c7495f42.png?resizew=189)
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解答题-证明题
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【推荐2】定义:有一个角为直角的平行四边形是矩形.
(1)如图1,在平行四边形
中,
,
是它的两条对角线,
.请用题中矩形定义证明:平行四边形
是矩形;
(2)如图2,在矩形
中,
是
的中点,将
沿
折叠后得到
,点
在矩形
内部,延长
交
于点
.猜想线段
与
有何数量关系?并证明你的结论;
(3)如图3,将(2)中的矩形
改为平行四边形,其它条件不变,(2)中的结论是否仍然成立,请说明理由.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/22/79d33e14-a176-42ba-8d56-cc738357d74c.png?resizew=403)
(1)如图1,在平行四边形
![](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/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7de966c316db1013defc56372fcf814e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(2)如图2,在矩形
![](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/e742966e3711cfa53dce04022acf4bcc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca2698f08d94afa1cd5b81444791f4c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8e5f736b1195fef1d2d300168a795f1.png)
(3)如图3,将(2)中的矩形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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解答题-作图题
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名校
【推荐1】已知四边形ABCD为矩形(AD>AB),
![](https://img.xkw.com/dksih/QBM/2022/3/28/2945929342631936/2946524035260416/STEM/1567314a-e6a5-4496-8efc-6529a0537933.png?resizew=243)
(1)尺规作图:在BC上取一点E,使AE=AD;过点D作DF⊥AE,交AE于点F(基本作图,保留作图痕迹,不写作法,);
(2)求证:DF=DC,(请补全下面的证明过程,不写证明理由)
证明:∵______①,
∴AD=BC,AD∥BC,∠B=90°,
∴∠FAD=∠AEB.
∵DF⊥AE,
∴______②.
∴______③.
在△AFD与△EBA中,
,
∴△AFD≌△EBA(AAS).
∴______④.
又∵AB=CD,
∴DF=DC.
![](https://img.xkw.com/dksih/QBM/2022/3/28/2945929342631936/2946524035260416/STEM/1567314a-e6a5-4496-8efc-6529a0537933.png?resizew=243)
(1)尺规作图:在BC上取一点E,使AE=AD;过点D作DF⊥AE,交AE于点F(基本作图,保留作图痕迹,不写作法,);
(2)求证:DF=DC,(请补全下面的证明过程,不写证明理由)
证明:∵______①,
∴AD=BC,AD∥BC,∠B=90°,
∴∠FAD=∠AEB.
∵DF⊥AE,
∴______②.
∴______③.
在△AFD与△EBA中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e66cd885e91cf8acbafb9db98c412010.png)
∴△AFD≌△EBA(AAS).
∴______④.
又∵AB=CD,
∴DF=DC.
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解答题-作图题
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【推荐2】如图,在
的格点图中,
为格点三角形,即顶点A、B、C均在格点上,利用无刻度直尺按要求完成下列各题,并保留作图痕迹;
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/30/630ccfe0-03b4-4557-9f8f-51211c9f3f9c.png?resizew=222)
(1)请在图①中
边上找一点M,使
:
(2)请在图②中
内部(不含边界)找一点N,使
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fb9d60d456560e9bac66c8b20c49bb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/30/630ccfe0-03b4-4557-9f8f-51211c9f3f9c.png?resizew=222)
(1)请在图①中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6800eee3929fc9b7b49769d2b2fda6e.png)
(2)请在图②中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd2a5881b7e5fdf6afdf408e3fe14663.png)
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解答题-计算题
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【推荐1】阅读下面材料:
小石遇到这样一个问题:图1,
分别是
的边
上的动点(不与点B重合),
与
的角平分线交于点P,
的周长为a,过点P作
于点
于点N,求
与
的周长a的数量关系.
小石通过测量发现了垂线段
与
的数量关系,从而构造全等三角形和直角三角形,经过推理和计算使问题得解决.
(1)线段
与
的数量关系为__________;
与a的数量关系是____________.
(2)如图2,当
时,其它条件不变,判断点P到
的距离
与
的周长a的数量关系,并简要说明理由.
小石遇到这样一个问题:图1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e5fdbfd4a1c3c268135c76036aa4c09.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50b5e3233c752c038002943d888cc71d.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c5d3f1c7f7ffdf572978468d5a3adde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abe4bdc5d9e833b23a1b916c06fc1a35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0eb7bc13f6f2e3f2de6ecf7c01a8981.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50f3a10030479306664e8ac3306d3600.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abe4bdc5d9e833b23a1b916c06fc1a35.png)
小石通过测量发现了垂线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/892909e49156f7dcc0650fcd65243877.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c8ffe24cf9f327aeb241225ab15ab1a.png)
(1)线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/892909e49156f7dcc0650fcd65243877.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c8ffe24cf9f327aeb241225ab15ab1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2bb1548ddc0e5536a35b1bd78c4e7cd.png)
(2)如图2,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e075468e7fb0bf30229aec01a7205977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35d58f9019097bd05037aefd5c322916.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abe4bdc5d9e833b23a1b916c06fc1a35.png)
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解答题-作图题
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【推荐1】如图所示的曲边三角形可按下述方法作出:作等边三角形
;分别以点A,B,C为圆心,以
的长为半径作
,
,
.三段弧所围成的图形就是一个曲边三角形,如果一个曲边三角形的周长为
,那么它的面积是多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed41d321f4c0717ac5b443aad942d9a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/667349d99185bb045030b733352ff7fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16d65cecaf8a3dc2953f4109c75a981e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
![](https://img.xkw.com/dksih/QBM/2021/10/20/2833513464651776/2842115137961984/STEM/d74b089150514f4da733a065d5c7dcd1.png?resizew=158)
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解答题-证明题
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【推荐2】如图,四边形
内接于
,直径
于点F,
,
的延长线交于点G,连接
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/23/83135fa9-83b0-4d8b-8b73-da33a02dbc72.png?resizew=173)
(1)求证:
;
(2)已知
,求图中阴影部分的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e3f5dc11efe60b4fd9a13b1d6b83842.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/d40b319212a7e7528b053e1c7097e966.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/23/83135fa9-83b0-4d8b-8b73-da33a02dbc72.png?resizew=173)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e729185071c0968fac76ba80a59d2964.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab09e8d4d0c92f630b0ce691d0ad7a85.png)
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