用一根长为40
的铁丝围成一个半径为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
的扇形,设扇形的面积为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
,求扇形的面积
与它的半径
之间的函数解析式.这个函数是二次函数吗?请写出半径
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efa9fbcfb9595e2f031aa691db4564b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d463bb27cb607a91c73b5610c0a5d2c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5265d50fd23c04af83e1bf0a937c5075.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
18-19九年级·全国·课后作业 查看更多[2]
更新时间:2019-12-17 07:21:01
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相似题推荐
解答题-证明题
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适中
(0.65)
【推荐1】如图,点
是正方形
边
上一点,过
作
的垂线,交
于点
,交
的延长线于点
.
![](https://img.xkw.com/dksih/QBM/2020/12/9/2616028061728768/2627419942879232/STEM/8741179d-cf30-49f9-aaf8-e15cd9c4cf70.png)
(1)若点
是
的中点,求证:
;
(2)若正方形的边长为4,
①当
取最大值时,
的长为多少?
②试确定
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://img.xkw.com/dksih/QBM/2020/12/9/2616028061728768/2627419942879232/STEM/8741179d-cf30-49f9-aaf8-e15cd9c4cf70.png)
(1)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/256f99e1a65655b86dd15424b5d73d69.png)
(2)若正方形的边长为4,
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
②试确定
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c63e36329f5e0979f5ee776ac5d06327.png)
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名校
【推荐2】如图,已知抛物线y=ax2+bx+3经过点A(﹣1,0)、B(3,0)两点,且交y轴交于点C.
(1)求抛物线的解析式;
(2)点M是线段BC上的点(不与B、C重合),过M作MN∥y轴交抛物线于N,若点M的横坐标为m,请用m的代数式表示MN的长;
(3)在(2)的条件下,连接NB,NC,是否存在点M,使△BNC的面积最大?若存在,求m的值;若不存在,说明理由.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/26/b5f89d3d-3a98-4700-9d2c-1c0911933d57.png?resizew=152)
(1)求抛物线的解析式;
(2)点M是线段BC上的点(不与B、C重合),过M作MN∥y轴交抛物线于N,若点M的横坐标为m,请用m的代数式表示MN的长;
(3)在(2)的条件下,连接NB,NC,是否存在点M,使△BNC的面积最大?若存在,求m的值;若不存在,说明理由.
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【推荐1】一款平板保护套放置在水平桌面上(如图1).当保护套展开时,其侧面示意图如图2甲所示.当平板保护套完全合拢时,点
与点
重合,点
与点
重合(如图2乙).已知
.
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/961632a0-19fd-4263-aaa0-442842054eb9.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/22602b7c-c03d-42cf-9e89-a9eb1f16b624.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/d3e63c9d-f5bc-4008-8073-3fc5613ed488.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/5e1c8dee-7c5a-4268-9d35-dd30ea70c35f.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/3aecb194-e523-4051-a58f-c1c7eeac3774.png)
(1)如图3,当点
与点
重合时,求
的度数(精确到度).
(2)如图4,点
从点
出发沿着
方向滑动.
①当点
滑动至
时,求点
的高度上升了多少厘米?
②当点
滑动至点
时,若
,求线段
扫过的面积(结果保留
).(参考数据:
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9fd059d20e1db7788f756c98ca04eab.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/961632a0-19fd-4263-aaa0-442842054eb9.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/22602b7c-c03d-42cf-9e89-a9eb1f16b624.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/d3e63c9d-f5bc-4008-8073-3fc5613ed488.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/5e1c8dee-7c5a-4268-9d35-dd30ea70c35f.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712452962312192/2715088429326336/STEM/3aecb194-e523-4051-a58f-c1c7eeac3774.png)
(1)如图3,当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
(2)如图4,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
①当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e075468e7fb0bf30229aec01a7205977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
②当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d676c6baf3d1b3696484f7dd372dd49f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5a122e25cf4eb9f03ffe5ec823bfc31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad57d1a81f526d6c1d4ad875d3cec29d.png)
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【推荐2】如图,圆O的直径为10 cm,两条直径AB,CD相交成90°角,∠AOE=50°,OF是∠BOE的平分线.
(1)求圆心角∠COF的度数;
(2)求扇形COF的面积.
(1)求圆心角∠COF的度数;
(2)求扇形COF的面积.
![](https://img.xkw.com/dksih/QBM/2018/8/23/2016602027319296/2017354836729856/STEM/2b15a4b7d6454ca7be69239059f1c36d.png?resizew=113)
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真题
【推荐3】如图,已知半圆O的直径DE=12cm,在△ABC中,∠ACB=90°,∠ABC=30°,BC=12cm,半圆O以2cm/s的速度从左向右运动,在运动过程中,点D、E始终在直线BC上.设运动时间为t(s),当t=0s时,半圆O在△ABC的左侧,OC=8cm.
(1)当t为何值时,△ABC的一边所在直线与半圆O所在的圆相切?
(2)当△ABC的一边所在直线与半圆O所在的圆相切时,如果半圆O与直线DE围成的区域与△ABC三边围成的区域有重叠部分,求重叠部分的面积.
(1)当t为何值时,△ABC的一边所在直线与半圆O所在的圆相切?
(2)当△ABC的一边所在直线与半圆O所在的圆相切时,如果半圆O与直线DE围成的区域与△ABC三边围成的区域有重叠部分,求重叠部分的面积.
![](https://img.xkw.com/dksih/QBM/2012/9/15/1573520151150592/1573520180502528/STEM/ee304d04-ad27-4f30-8076-4dbe3de1764e.png?resizew=327)
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