如图,在矩形ABCD中,AB=
,BC=1,把矩形ABCD绕点A顺时针旋转30°得到矩形AB′C′D′,其中点C的运动路径为
,则图中阴影部分的面积为( )
![](https://img.xkw.com/dksih/QBM/2020/12/17/2615877899657216/2618416265920512/STEM/3f931b57212744a6b1e9aaca5a1655e5.png?resizew=164)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c236cc0f297f86bef73b31fbfce3c8c.png)
![](https://img.xkw.com/dksih/QBM/2020/12/17/2615877899657216/2618416265920512/STEM/3f931b57212744a6b1e9aaca5a1655e5.png?resizew=164)
A.![]() | B.![]() | C.![]() | D.![]() |
20-21九年级上·湖南长沙·期中 查看更多[3]
湖南省长沙市岳麓区师大附中博才实验中学2020-2021学年九年级上学期期中数学试题(已下线)必刷卷02-2021年中考数学考前信息必刷卷(湖南长沙专用)(已下线)28.1.3 特殊角的三角函数值(分层练习)-2022-2023学年九年级数学下册同步精品课堂(人教版)
更新时间:2020-12-30 21:08:01
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【推荐1】如图,矩形ABCD中,AB=3,BC=4,点E是AB边上一点,且AE=2,点F是边BC上的任意一点,把△BEF沿EF翻折,点B的对应点为G,连接AG,CG,则三角形AGC的面积的最小值为( )
![](https://img.xkw.com/dksih/QBM/2022/3/23/2942242410070016/2955274752819200/STEM/e31001c5-dd54-43ee-9f12-88ff1bc334c4.png?resizew=201)
![](https://img.xkw.com/dksih/QBM/2022/3/23/2942242410070016/2955274752819200/STEM/e31001c5-dd54-43ee-9f12-88ff1bc334c4.png?resizew=201)
A.![]() | B.![]() |
C.![]() | D.![]() |
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【推荐2】如图,矩形
矩形
,连结
,延长
分别交
、
于点
、
,延长
、
交于点
,一定能求出
面积的条件是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/18/c53d0abe-cccf-4526-adef-1e972add7726.png?resizew=153)
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A.矩形![]() ![]() | B.矩形![]() ![]() |
C.矩形![]() ![]() | D.矩形![]() ![]() |
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【推荐1】如图,在Rt△ABC中,∠ACB=90°,AC=BC=
,将Rt△ABC绕A点按逆时针方向旋转30°后得到Rt△ADE,点B经过的路径为弧BD,则图中阴影部分的面积是( )
![](https://img.xkw.com/dksih/QBM/2015/7/6/1573864174731264/1573864179974144/STEM/6d74d0e8-b53b-4bc1-b28b-22d4c5204451.png?resizew=185)
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A.![]() | B.![]() | C.![]() | D.![]() |
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【推荐2】我们研究过的图形中,圆的任何一对平行切线的距离总是相等的,所以闹息“等宽曲线”.除了圆以外,还有一些几何图形也是“等宽曲线”,如勒洛三角形(如图1),它是分别以等边三角形的每个顶点为圆心,以边长为半径,在另两个顶点间画一段圆弧,三段圆弧围成的曲边三角形.图2是等宽的勒洛三角形和圆形滚木的截面图( )
,则勒洛三角形的周长为
;④图3中,在
中随机以一点,则该点取自勒洛三角形
部分的概率为
,上述结论中,所有正确结论的序号是( )
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A.①② | B.②④ | C.②③ | D.③④ |
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【推荐1】如图,扇形
中,
,
,点
为
的中点,将扇形
绕点
顺时针旋转
,得到扇形
,则图中阴影部分的面积为( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/27/78e8b44c-4e6a-4280-9b91-3e5cc08e9bdf.png?resizew=177)
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【推荐2】已知
为锐角,且
tan2
-(1+
)tan
+1=0,则
的度数为( )
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A.30° | B.45° | C.30°或45° | D.45°或60° |
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