如图所示,在□
中,已知点
分别在
上,且
.则四边形
是平行四边形吗?若是,请证明.
![](https://img.xkw.com/dksih/QBM/2013/4/26/1573644626067456/1573644631875584/STEM/672ef95360f74ac29c32708bf6cb8c18.png)
![](https://img.xkw.com/dksih/QBM/2013/4/26/1573644626067456/1573644631875584/STEM/0703de3459534815917ab4c3a1c3e084.png)
![](https://img.xkw.com/dksih/QBM/2013/4/26/1573644626067456/1573644631875584/STEM/f7f4d3f7891845d98580bc6e87339f95.png)
![](https://img.xkw.com/dksih/QBM/2013/4/26/1573644626067456/1573644631875584/STEM/49912fbbffc744268ed755df8daf1b38.png)
![](https://img.xkw.com/dksih/QBM/2013/4/26/1573644626067456/1573644631875584/STEM/534f29ee86204398ba6d4ee951958bcd.png)
![](https://img.xkw.com/dksih/QBM/2013/4/26/1573644626067456/1573644631875584/STEM/b0bc1863f35b4be0926496d37ce67492.png)
更新时间:2016-12-05 17:31:06
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【知识点】 证明四边形是平行四边形解读
相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图,以△ABC的三边为边,在BC的同侧作三个等边△ABD、△BEC、△ACF.
![](https://img.xkw.com/dksih/QBM/2015/9/24/1573915409391616/1573915415863296/STEM/c820aeaff5a44d978d6f1a1cd8a962bd.png)
(1)判断四边形ADEF的形状,并证明你的结论;
(2)当△ABC满足什么条件时,四边形ADEF是菱形?是矩形?
![](https://img.xkw.com/dksih/QBM/2015/9/24/1573915409391616/1573915415863296/STEM/c820aeaff5a44d978d6f1a1cd8a962bd.png)
(1)判断四边形ADEF的形状,并证明你的结论;
(2)当△ABC满足什么条件时,四边形ADEF是菱形?是矩形?
您最近一年使用:0次
解答题-作图题
|
适中
(0.65)
名校
【推荐2】如图,在四边形
中,
,
,
上截取
,作
交
于点F;
(保留作图痕迹,不写作法)
(2)在(1)所作图形中,求证:
(请补全下面的证明过程,不写证明理由)
证明:∵![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4adf90a8c2b29334cdc5aa5b554991f9.png)
∴ ①![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4df89e372474c87ac158a7b8f22e27b8.png)
∵![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0095edf048d91dc2910056a866febb5a.png)
∴ ②
∴ ③
∴四边形
为平行四边形
∵![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29ee224ad0d3ac27adcc7c4d7684fe78.png)
∴ ④
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4adf90a8c2b29334cdc5aa5b554991f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/deb6694f3443cc5f4d09948679251b61.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3620030e8808da46df97330103827913.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0095edf048d91dc2910056a866febb5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
(保留作图痕迹,不写作法)
(2)在(1)所作图形中,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efbc0e76b7abb656327bdc97226713e1.png)
证明:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4adf90a8c2b29334cdc5aa5b554991f9.png)
∴ ①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4df89e372474c87ac158a7b8f22e27b8.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0095edf048d91dc2910056a866febb5a.png)
∴ ②
∴ ③
∴四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18d5a164bf56f8fb92527ad78bc10ccf.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29ee224ad0d3ac27adcc7c4d7684fe78.png)
∴ ④
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efbc0e76b7abb656327bdc97226713e1.png)
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