如图,等腰直角△ABC中,∠BAC=90°,AB=AC,∠ADB=45°
![](https://img.xkw.com/dksih/QBM/2019/12/28/2364627687301120/2368293067464704/STEM/abeaf0ca7a4f442c91234cbee9bc3899.png?resizew=168)
(1)求证:BD⊥CD;
(2)若BD=6,CD=2,求四边形ABCD的面积.
![](https://img.xkw.com/dksih/QBM/2019/12/28/2364627687301120/2368293067464704/STEM/abeaf0ca7a4f442c91234cbee9bc3899.png?resizew=168)
(1)求证:BD⊥CD;
(2)若BD=6,CD=2,求四边形ABCD的面积.
更新时间:2020-01-02 10:47:29
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【知识点】 旋转模型(全等三角形的辅助线问题)解读
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解答题-证明题
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【推荐1】一幅三角板Rt△ABC和Rt△DEF按如图1摆放,点E, A, D, B在一条直线上,且D是AB的中点,将Rt△DEF绕点D顺时针方向旋转
(0°<
<90°)角,在旋转过程中,直线DE与AC相交于点M,直线DF与BC相交于点N,分别过点M, N作直线AB的垂线,垂足分别为G, H.
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/5d378b27-2cf9-4e60-84ca-68a4fde42dd0.png)
(1)当
=30°时(如图2),求证:AG=DH;
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/76ea7b47-799d-4557-b02d-7fea08f0cd30.png)
(2)当
=60°时(如图3),(1)中的结论是否仍成立?请写出你的结论,并说明理由.
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/482c2d6faab04837a2002680cae2f5fb.png)
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/482c2d6faab04837a2002680cae2f5fb.png)
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(1)当
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/482c2d6faab04837a2002680cae2f5fb.png)
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/76ea7b47-799d-4557-b02d-7fea08f0cd30.png)
(2)当
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/482c2d6faab04837a2002680cae2f5fb.png)
![](https://img.xkw.com/dksih/QBM/2013/12/24/1573692419743744/1573692426010624/STEM/9c7bcb24-5574-47f3-bdca-613133205c29.png)
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【推荐2】某数学兴趣小组在探究“手拉手”模型时,等边三角形
和
按如图1摆放,连接
延长
交
于点F,连接
,保持
不动,将
绕点A旋转.
,
重合时,请直接写出
之间的数量关系:______;
【深入探究】(2)如图1,当点E,F不重合时,(1)中的结论是否仍然成立?若成立,请给出推理过程;若不成立,请说明理由.
【拓展延伸】(3)如图3,当
和
都是等腰直角三角形,
.连接
延长
交
于点F,连接
,试探究
之间的数量关系,并说明理由.
【推广应用】(4)如图4,在
中,若
.连接
延长
交
于点F,连接
,请直接写出
之间的数量关系:______;
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【拓展延伸】(3)如图3,当
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79ff575e55857af133edb24c8e61504f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08a50b9dbe5e8c960fb848f425006984.png)
【推广应用】(4)如图4,在
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