如图1,在等边三角形
中,
,射线
,点E从点A出发沿射线
以
的速度运动,同时点F从点B出发沿射线
以
的速度运动,设点E的运动时间为
.
,若
经过边
的中点D.
①求证:四边形
是平行四边形;
②求此时t的值.
(2)是否存在t,使得以点A,E,C,F为顶点的四边形为菱形?若存在,求出t的值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c545764505bb00578a870c5e39493a3e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de13b90ee61450dcf26f2f04b010b3b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a7e4a6765ce78b05ee97764771e01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5631e6ec24d3d67bf4592313b6b3f4f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d989a128e30a701dfff5592476a76bab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d744165d6aad705f64de41a9d931750a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
①求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9766e5eb6796dafc5ffe212afdfc43c0.png)
②求此时t的值.
(2)是否存在t,使得以点A,E,C,F为顶点的四边形为菱形?若存在,求出t的值;若不存在,请说明理由.
更新时间:2024-06-03 15:16:23
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相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】在正方形
中,E是
边上一点(点E不与点B,C重合),
,
与正方形的外角
的平分线交于点F.
(1)如图1,若点E是
的中点,猜想
与
的数量关系是 ;证明此猜想时,可取
的中点P,连接
.根据此图形易证
.则判断
的依据是 .
(2)点E在
边上运动.
①如图2,(1)中的猜想是否仍然成立?请说明理由.
②如图3,连接
,
,若正方形
的边长为1,直接写出
的周长c的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bce726bceb02452bb4e5ed6b00fa94e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c7a82bf203df79ba6c0ef80026198d1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/26/4b435a95-2a4d-4065-90be-3d2ed1a05763.png?resizew=620)
(1)如图1,若点E是
![](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/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f541f7ae7c39082d202efd28805c54e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cb60ec1edd71456e010cf250ad74af2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cb60ec1edd71456e010cf250ad74af2.png)
(2)点E在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
①如图2,(1)中的猜想是否仍然成立?请说明理由.
②如图3,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d79c5041878c15de69253ca11a03ab1b.png)
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【推荐2】如图,四边形
是矩形,
是
上的一点,
,
.点
是
、
延长线的交点,
与
相交于点
.
(1)求证:四边形
是正方形;
(2)当
,
时,求
的值.
![](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/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b62617f3845f87e688c2cdf2bbc4c65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2226397b9bdbc77087433b05fb61209.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a7e4a6765ce78b05ee97764771e01f.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/8/bce71924-9504-41b5-a047-dbf55cd0405e.png?resizew=107)
(1)求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d93fd14603fafb45407feb3146155a17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faac29dffda6ed545dbebd016cc82185.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0e57a13c665af88f326c9890072bf73.png)
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【推荐1】如图,在△ABC中,AD平分∠BAC交BC于点D.点E、F分别在边AB、AC上,且BE=AF,FG∥AB交线段AD于点G,连接BG、EF.
(1)求证:四边形BGFE是平行四边形;
(2)若△ABG∽△AGF,AB=10,AG=6,求线段BE的长.
(1)求证:四边形BGFE是平行四边形;
(2)若△ABG∽△AGF,AB=10,AG=6,求线段BE的长.
![](https://img.xkw.com/dksih/QBM/2019/1/23/2124805891727360/2168306761211904/STEM/e468ac255eac4ac19f6d4308d09be719.png?resizew=188)
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名校
【推荐2】如图,在
中,
,
是
的中点,
是
的中点,过点
作
交
的延长线于点
.
(1)求证:
;
(2)求证:四边形
是菱形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.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/2a30f3a8b673cc28bd90c50cf1a35281.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/880efdb2b4ac4861ad808e0162d082be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/11/ce1f2637-5612-4856-8afc-2b436b304c17.png?resizew=222)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e2e1083b773e16d1e385072652f7319.png)
(2)求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94a5a2949b3d520ed03d57126c7d4d8d.png)
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【推荐1】如图所示,在梯形ABCD中,AD∥BC,E,F,M,N分别为AD,AB,BC,CD的中点,连接EF,FM,MN,EN,你能肯定四边形EFMN是平行四边形吗?为什么?若将梯形ABCD改变成等腰梯形,其他条件不变,你又会得到EFMN是什么四边形呢?为什么?
![](https://img.xkw.com/dksih/QBM/2018/8/21/2015263662497792/2048436432232448/STEM/cd9a5353343347379c086fc7add78c69.png?resizew=300)
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【推荐2】小明学习菱形时,对矩形
进行了画图探究
,其作法和图形如下:
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/11/b11a5bdc-76d7-4ef1-a105-e2cde2df7c9f.png?resizew=130)
①连接
;
②分别以点
,
为圆心,大于
长的一半为半径作弧,两弧相交于
,
两点,作直线
交
于点
,交
于点
,交
于点
;
③连接
,
.
(1)根据以上作法,判断四边形
的形状,并说明理由;
(2)若
,
,求四边形
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f433ff0d49919d797194297c0bd4c67c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/11/b11a5bdc-76d7-4ef1-a105-e2cde2df7c9f.png?resizew=130)
①连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
②分别以点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.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/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)
③连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
(1)根据以上作法,判断四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c87e1fe20bb0e8292e993657e14bc79a.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04ee826937d2add7a93aaa1422f8b736.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c87e1fe20bb0e8292e993657e14bc79a.png)
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