以线段AC为对角线的凸四边形ABCD(它的四个顶点A、B、C、D按顺时针方向排列,每个内角均小于180°),已知AB=BC=CD,∠ABC=120°,∠CAD=30°,则∠BCD的大小为____________ .
更新时间:2017-06-01 05:06:49
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【推荐1】已知:如图,△ABC是等边三角形,延长AC到E,C为线段AE上的一动点(不与点A、E重合),在AE同侧分别作正三角形ABC和正三角形CDE,AD与BE交于点O,AD与BC交于点P,BE与CD交于点Q,连接PQ,OC. 以下五个结论:①AD=BE;②AP=BO;③PQ//AE;④∠AOB=60°;⑤OC平分∠AOE;结论正确的有_________ (把你认为正确的序号都填上)
![](https://img.xkw.com/dksih/QBM/2019/11/27/2342787411714048/2345104074530816/STEM/85929458c45e4336bba704da119d2c7c.png?resizew=154)
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【推荐2】如图,
为等边三角形,点
为
外的一点,
,
,则
的面积为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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【推荐1】如图,已知正方形ABCD的边长为4,点E在CD边上,EC=3DE,点F在AD边上(异于点C),且∠AFE=∠AFB,则BF长为______ .
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【推荐2】如图,在矩形ABCD中,AD=6,AB=4,点E、G、H、F分别在AB、BC、CD、AD上,且AF=CG=2,BE=DH=1,点P是直线EF、GH之间任意一点,连接PE、PF、PG、PH,则△PEF和△PGH的面积和等于________ .
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【推荐1】如图,
ABC中,AC=BC,且点D在
ABC外,D在AC的垂直平分线上,连接BD, 若∠DBC=30°∠ACD=13°,则∠A=_________ °
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【推荐2】如图,在四边形
中,
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,
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上一点,
,F为直线
上的动点,连接
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【推荐1】如图,
,过
上到点
的距离分别为
的点作
的垂线与
相交,得到并标出一组黑色梯形,它们的面积分别为
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____ .
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【推荐2】如图,梯形ABCD中,
,
,将线段CB绕着点B按顺时针方向旋转,使点C落在CD延长线上的点E处.联结AE、BE,设BE与边AD交于点F,如果
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