1 . 定义:对于一个凸四边形,我们把依次连接它的各边中点得到的新四边形叫做原四边形的“中点四边形”,如果原四边形的中点四边形是个正方形,我们把这个原四边形叫做“中正四边形”.
A.平行四边形 B.矩形 C.菱形 D.正方形
(2)性质探究:如图
,四边形
是“中正四边形”,观察图形,直接写出关于四边形
对角线的两条结论;
(3)问题解决:如图
,
为锐角三角形,以
的两边
,
为边长,分别向外侧作正方形
和正方形
,连接
,
,
,求证:四边形
是“中正四边形”.
A.平行四边形 B.矩形 C.菱形 D.正方形
(2)性质探究:如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(3)问题解决:如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.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/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad3a079cfdcca9acdacecbf08f9f78cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff7a0bfc593a8a33b6cade6ba213904c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e55e398e8520d8a36fb5a625a085b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8e5f736b1195fef1d2d300168a795f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/693cd6179b2a92f03153ce12a0e86b95.png)
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解题方法
2 . 综合实践
数学课上,各小组进行了特殊四边形的探究活动,如图所示,在
中,分别以
,
,
为边在
的同侧作等边三角形
,等边三角形
,等边三角形
.
![](https://img.xkw.com/dksih/QBM/2020/11/5/2586372156088320/2588027229396992/STEM/7e060cbb000b457395a0f0c7eda36f30.png?resizew=156)
(1)奋进小组发现:四边形
是平行四边形,请你完成证明;
(2)当四边形
是矩形时,求
的度数;
(3)当四边形
是菱形时,若
,请直接写出
与
之间的数量关系.
数学课上,各小组进行了特殊四边形的探究活动,如图所示,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c66d99a6a8415ddad22bbed33b64cfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a09d9d486b7f91ba933210dd013a7f2c.png)
![](https://img.xkw.com/dksih/QBM/2020/11/5/2586372156088320/2588027229396992/STEM/7e060cbb000b457395a0f0c7eda36f30.png?resizew=156)
(1)奋进小组发现:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fe65a9d11595427706080b3e9f8d68b.png)
(2)当四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fe65a9d11595427706080b3e9f8d68b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbce11aa19b8bd2bf6ee5a834e005de.png)
(3)当四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fe65a9d11595427706080b3e9f8d68b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a1b8d111d101afbbf301a2c56c6d15e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
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