如图, AD为△ABC的中线,BE为△ABD的中线.
(1)∠ABE=15°,∠BAD=36°,求∠BED的度数;
(2)作出△BED中DE边上的高,垂足为H;
(3)若△ABC面积为20,过点C作CF//AD交BA的延长线于点F,求△BCF的面积.(友情提示:两条平行线间的距离处处相等.)
(1)∠ABE=15°,∠BAD=36°,求∠BED的度数;
(2)作出△BED中DE边上的高,垂足为H;
(3)若△ABC面积为20,过点C作CF//AD交BA的延长线于点F,求△BCF的面积.(友情提示:两条平行线间的距离处处相等.)
![](https://img.xkw.com/dksih/QBM/2014/5/21/1573729657487360/1573729663369216/STEM/548d0c57-5be7-4093-95cb-8955b4b5d6d9.png?resizew=231)
更新时间:2016-12-05 20:24:06
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解答题-作图题
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较难
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【推荐1】如图是由小正方形组成的
网格,每个小正方形的顶点叫做格点.
、
、
三点是格点,
,
分别是
,
与网格线的交点,仅用无刻度直尺在给定网格中完成画图.
(1)在图1中,取
的中点
,
的中点
,连接
;再作平行四边形
;
(2)在图2中,在
上画出一点
,使
;
(3)在图2中,在
的边
上画一点M,使得
是正方形
的一个顶点,且正方形的顶点
在
上,顶点
、
在
上.(只需画出点
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6250504f1fd1969cae8f691ca75543c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/19/dd86f284-74cb-4980-a433-ed5055da2651.png?resizew=243)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/19/ba5f25ae-c30e-4ae0-8e1b-56b99581ed5c.png?resizew=239)
(1)在图1中,取
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21037e170bdbb322558e79c40c00b454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6025e9005912f5e158bde206c3de9a6.png)
(2)在图2中,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cae230dcb264ae327ffe949e68624758.png)
(3)在图2中,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8059a935a2325a9e7abbcbf56aa167f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b1ec05e3cec27677ded7b4aecaa62d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b198c11743c430115a45d37efb163ea7.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7bf58e5fea1189b33cf55d86335452f.png)
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解答题-证明题
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【推荐2】(1)如图1,在
中,
,
平分
,交
于点D,
,交
于点E.
①证明:
.
②试探究
是否为定值.如果是,请求出这个定值;如果不是,请说明理由.
(2)如图2,
和
是
的2个外角,
,CD平分
,交AB的延长线于点D,
,交CB的延长线于点E.记
的面积为
,
的面积为
,
的面积为
.若
,求
的值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/30/7fd09c09-84e9-4ae3-8285-bf9e8cec0df9.png?resizew=193)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b903796831a684296f24e836b1fa7770.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fabb884dc5f9609de491245463bbe9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/105068b25f5a63af32f4082cfe08691e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
①证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ceef27cdf992447ab4c36c2b936670b.png)
②试探究
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4705575bc87b811f07ca57d89b22c75.png)
(2)如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67306e4c11034d33babf27e837f9e4dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfd94dd51562ecbee6edd4265326b765.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdfd268523ec8027e4ff6bc3cfbb8141.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfd94dd51562ecbee6edd4265326b765.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/105068b25f5a63af32f4082cfe08691e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ac451db3443cabb204f96c31fd4a02e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d631f45bc652539853f236952afa5bbf.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167c73d407a112d8d323b733a45f070d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54f1dbb70902c9f9cc16f39d6572819c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/30/7fd09c09-84e9-4ae3-8285-bf9e8cec0df9.png?resizew=193)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/30/0bd0f8cf-9f8f-45d1-80cd-cbf7339d64c3.png?resizew=238)
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解答题-作图题
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较难
(0.4)
【推荐1】在网格中作图,
的顶点在格点处(单位长度为1,只能用直尺画图)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/20/96798caf-f8ff-4ae9-9b96-1623ca112913.png?resizew=190)
(1)过B点,作
的平行线
;
(2)作
边上的高
;
(3)作
边上的中线
;
(4)直接写出
的面积;
(5)直接写出
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/20/96798caf-f8ff-4ae9-9b96-1623ca112913.png?resizew=190)
(1)过B点,作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
(2)作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
(3)作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
(4)直接写出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(5)直接写出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbce11aa19b8bd2bf6ee5a834e005de.png)
您最近一年使用:0次
解答题-作图题
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【推荐2】在如图所示的网格中建立平面直角坐标系,
的顶点坐标分别为
,
,
,仅用无刻度的直尺在给定网格中完成画图,画图过程用虚线表示,并回答下列问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/23/c888115c-1c0a-4f6d-aebd-36c3e86db075.png?resizew=280)
(1)
的形状为______;
(2)画出
边上的高
;
(3)画出点
关于
的对称点
;
(4)已知点
,点
在线段
上,若
,则点
的坐标为______.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf5a6145990adf5574f0e0f2fc828ea4.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/23/c888115c-1c0a-4f6d-aebd-36c3e86db075.png?resizew=280)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)画出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(3)画出点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
(4)已知点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff2595e01e8751886a27862cce04e2d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d76fc72eb26ffe8516bce410a416a456.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
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解答题-问答题
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【推荐1】探索:在图
至图
中,已知
的面积为
,
![](https://img.xkw.com/dksih/QBM/2022/10/14/3087599485829120/3095909094531072/STEM/18702dd7921747bf88a4bec19d4b4544.png?resizew=368)
(1)如图
,延长
的边
到点
,使
,连接
若
的面积为
,则
______
用含
的代数式表示![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04582116cd765fcc5a52f44279ad6c94.png)
(2)如图
,延长
的边
到点
,延长边
到点
,使
,
,连接
若
的面积为
,则
______
用含
的代数式表示![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04582116cd765fcc5a52f44279ad6c94.png)
(3)在图
的基础上延长
到点
,使
,连接
,
,得到
(如图)若阴影部分的面积为
,则
______
用含
的代数式表示![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04582116cd765fcc5a52f44279ad6c94.png)
(4)发现:像上面那样,将
各边均顺次延长一倍,连接所得端点,得到
如图
,此时,我们称
向外扩展了一次.可以发现,扩展一次后得到的
的面积是原来
面积的______倍.
(5)应用:要在一块足够大的空地上栽种花卉,工程人员进行了如下的图案设计:首先在
的空地上种红花,然后将
向外扩展三次
图
已给出了前两次扩展的图案
在第一次扩展区域内种黄花,第二次扩展区域内种紫花,第三次扩展区域内种蓝花.如果种红花的区域
即
的面积是
平方米,请你运用上述结论求出:
①种紫花的区域的面积;
②种蓝花的区域的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://img.xkw.com/dksih/QBM/2022/10/14/3087599485829120/3095909094531072/STEM/18702dd7921747bf88a4bec19d4b4544.png?resizew=368)
(1)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19a1bf64ba772922fe58b5322eb4bced.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76bfc0e2ef648e5ded362b2eaafedd27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ac451db3443cabb204f96c31fd4a02e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ac8a4086cd8af00e89c57fdfd905114.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8e9cffeb4534c9fb9ee690be3b75b2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a301324443eb93b467134a86890dd9ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04582116cd765fcc5a52f44279ad6c94.png)
(2)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/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9abaeba15f3abdd877bc701af52c5cd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19a1bf64ba772922fe58b5322eb4bced.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92fa7f059542264fbbcae42704322b1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f32c425e7a8ed6d0d79c6e8e2df4302.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2689f0ce5ab3467d8214794d8acb2bd6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd72016a9855cbf0056ff732fe872612.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f36a32af52e0fa502ef1d03049f2504.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a301324443eb93b467134a86890dd9ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04582116cd765fcc5a52f44279ad6c94.png)
(3)在图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51bb339ba41929e8f693b3618d5ee4b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00bab17635a999236e8d2e35017a208d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7c57b07f75e97d9f84718bd495ebcf4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72cb97395ebc5ee1b212afb7a97b985c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1002e596b542ab2f5fb91f7b6d854f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddf942c3c3bb7e04e625f41fc0ddd940.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a301324443eb93b467134a86890dd9ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04582116cd765fcc5a52f44279ad6c94.png)
(4)发现:像上面那样,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4749e4eeadfa3ba5ce1c3e7f31aa0f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41e1e60ea83747caf1e9ddec6605747e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72cb97395ebc5ee1b212afb7a97b985c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(5)应用:要在一块足够大的空地上栽种花卉,工程人员进行了如下的图案设计:首先在
![](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/fd995178601c2ad7b40f973d268c7bb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/913b7537e011acfeec11952731351388.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd995178601c2ad7b40f973d268c7bb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e044325ad7fdaef36758daa8b9fe4456.png)
①种紫花的区域的面积;
②种蓝花的区域的面积.
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【推荐2】如图,点
,
分别是
的边
,
上的点,直线
与
交于点
,已知
,
,
的面积分别为3,4,5,求四边形
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8414369aceaa4231d66c698380926b14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0391623efe44c5b1e5d496c23109d36b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a00d05c60999eff91345a545fb57e9af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/946c16d99496d31ce4d87301a4793393.png)
![](https://img.xkw.com/dksih/QBM/2019/7/2/2238231460962304/2238417986781184/STEM/a01e64ad42514015a9f5ba53bae8c82f.png?resizew=81)
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名校
【推荐3】如图1,△ABC中,AD为BC边上的的中线,则S△ABD= S△ADC.
![](https://img.xkw.com/dksih/QBM/2016/5/3/1574201616883712/1574201623109632/STEM/3307ed3c-fe12-4bc9-8ced-813586753d11.png?resizew=659)
实践探究
(1)在图2中,E、F分别为矩形ABCD的边AD、BC的中点,则S阴和S矩形ABCD之间满足的关系式为 ;
(2)在图3中,E、F分别为平行四边形ABCD的边AD、BC的中点,则S阴和S平行四边形ABCD之间满足的关系式为 ;
(3)在图4中,E、F分别为任意四边形ABCD的边AD、BC的中点,则S阴和S四边形ABCD之间满足的关系式为 ;
解决问题:
(4)在图5中,E、G、F、H分别为任意四边形ABCD的边AD、AB、BC、CD的中点,并且图中阴影部分的面积为20平方米,求图中四个小三角形的面积和是多少?即求S1+ S2+ S3+ S4=?
![](https://img.xkw.com/dksih/QBM/2016/5/3/1574201616883712/1574201623109632/STEM/3307ed3c-fe12-4bc9-8ced-813586753d11.png?resizew=659)
实践探究
(1)在图2中,E、F分别为矩形ABCD的边AD、BC的中点,则S阴和S矩形ABCD之间满足的关系式为 ;
(2)在图3中,E、F分别为平行四边形ABCD的边AD、BC的中点,则S阴和S平行四边形ABCD之间满足的关系式为 ;
(3)在图4中,E、F分别为任意四边形ABCD的边AD、BC的中点,则S阴和S四边形ABCD之间满足的关系式为 ;
解决问题:
(4)在图5中,E、G、F、H分别为任意四边形ABCD的边AD、AB、BC、CD的中点,并且图中阴影部分的面积为20平方米,求图中四个小三角形的面积和是多少?即求S1+ S2+ S3+ S4=?
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【推荐1】图1是李晨在一次课外活动中所做的问题研究:他用硬纸片做了两个三角形,分别为△ABC和△DEF,其中∠B=90°,∠A=45°,BC=
,∠F=90°,∠EDF=30°, EF=2.将△DEF的斜边DE与△ABC的斜边AC重合在一起,并将△DEF沿AC方向移动.在移动过程中,D、E两点始终在AC边上(移动开始时点D与点A重合).
![](https://img.xkw.com/dksih/QBM/2014/7/18/1573739851513856/1573739857862656/STEM/92875ac047b14a9e96edcd47b91cfdaa.png?resizew=503)
(1)请回答李晨的问题:若CD=10,则AD= ;
(2)如图2,李晨同学连接FC,编制了如下问题,请你回答:
①∠FCD的最大度数为 ;
②当FC
AB时,AD= ;
③当以线段AD、FC、BC的长度为三边长的三角形是直角三角形,且FC为斜边时,AD=——;
④△FCD的面积s的取值范围是 .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ec978eb43bc4f9e7df83b0d0195dcda.png)
![](https://img.xkw.com/dksih/QBM/2014/7/18/1573739851513856/1573739857862656/STEM/92875ac047b14a9e96edcd47b91cfdaa.png?resizew=503)
(1)请回答李晨的问题:若CD=10,则AD= ;
(2)如图2,李晨同学连接FC,编制了如下问题,请你回答:
①∠FCD的最大度数为 ;
②当FC
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/638537c0a30676c73fea76c80e0f8bd0.png)
③当以线段AD、FC、BC的长度为三边长的三角形是直角三角形,且FC为斜边时,AD=——;
④△FCD的面积s的取值范围是 .
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【推荐2】如图,△ABC的角平分线相交于P,∠A=m°,
![](https://img.xkw.com/dksih/QBM/2018/3/28/1911761007255552/1915655019634688/STEM/4ce06829682d4db58bc3aec40a0ae35f.png?resizew=164)
(1)若∠A=40°,求∠BPC的度数;
(2)设△ABC的外角∠CBD、∠BCE的平分线相交于Q, 且∠A=m°,求∠BQC的度数
![](https://img.xkw.com/dksih/QBM/2018/3/28/1911761007255552/1915655019634688/STEM/4b7d52a66918449db464df8f96aeb60d.png?resizew=159)
(3)设△ABC的外角∠CBD、∠BCE的n等分线相交于R,且∠A=m°,∠CBR=
∠CBD,∠BCR=
∠BCE,求∠BRC的度数
![](https://img.xkw.com/dksih/QBM/2018/3/28/1911761007255552/1915655019634688/STEM/4ce06829682d4db58bc3aec40a0ae35f.png?resizew=164)
(1)若∠A=40°,求∠BPC的度数;
(2)设△ABC的外角∠CBD、∠BCE的平分线相交于Q, 且∠A=m°,求∠BQC的度数
![](https://img.xkw.com/dksih/QBM/2018/3/28/1911761007255552/1915655019634688/STEM/4b7d52a66918449db464df8f96aeb60d.png?resizew=159)
(3)设△ABC的外角∠CBD、∠BCE的n等分线相交于R,且∠A=m°,∠CBR=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ba0624131a82dc6bae78c8959e4fa34.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ba0624131a82dc6bae78c8959e4fa34.png)
![](https://img.xkw.com/dksih/QBM/2018/3/28/1911761007255552/1915655019634688/STEM/823dea35b4584ac3b4a6d17ce84e77b3.png?resizew=146)
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