已知:如图,四边形ABCD内接于⊙O,对角线AC为⊙O的直径,点E在CD的延长上,且∠EAD=∠ABD.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/11/7576899e-9bca-4edf-9f1a-486d2829a086.png?resizew=151)
(1)求证:AE是⊙O的切线;
(2)若BD//AE,AB=6,⊙O的半径为5,求AE的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/11/7576899e-9bca-4edf-9f1a-486d2829a086.png?resizew=151)
(1)求证:AE是⊙O的切线;
(2)若BD//AE,AB=6,⊙O的半径为5,求AE的长.
21-22九年级上·江苏盐城·期末 查看更多[3]
江苏省盐城市盐城景山中学2021-2022学年九年级上学期期末数学试题江苏省盐城市东台市2021-2022学年九年级上学期期末数学试题(已下线)专题3.54 圆中的相似问题(基础篇)(专项练习)-2022-2023学年九年级数学下册基础知识专项讲练(北师大版)
更新时间:2022-02-26 21:37:44
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【推荐1】如图1,在Rt△ABC中,∠ABC=90°,AB=BC=4,点D、E分别是边AB、AC的中点,连接DE,将△ADE绕点A按顺时针方向旋转,记旋转角为α,BD、CE所在直线相交所成的锐角为β.
(1)问题发现当α=0°时,
=_____;β=_____°.
(2)拓展探究
试判断:当0°≤α<360°时,
和β的大小有无变化?请仅就图2的情形给出证明.
(3)在△ADE旋转过程中,当DE∥AC时,直接写出此时△CBE的面积.
(1)问题发现当α=0°时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8775dcf60ad143bc59a58b000f374c56.png)
(2)拓展探究
试判断:当0°≤α<360°时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8775dcf60ad143bc59a58b000f374c56.png)
(3)在△ADE旋转过程中,当DE∥AC时,直接写出此时△CBE的面积.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/31/a1ad1957-6507-4359-acc5-7aaab9ebda2f.png?resizew=267)
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【推荐1】如图,点A的坐标为(3,0),以点A为圆心,5个单位长度为半径画圆,分别交x轴于点B、C,交y轴于点E、F.求点B、C、E、F的坐标.
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【推荐2】如图1是博物馆展出的古代车轮实物,《周礼·考工记》记载:“……故兵车之轮六尺有六寸,田车之轮六尺有三寸……”据此,我们可以通过计算车轮的半径来验证车轮类型,请将以下推理过程补充完整.
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如图2所示,在车轮上取A、B两点,设弧
所在圆的圆心为O,半径为
.作弦
的垂线
,D为垂足,则D是
的中点.其推理的依据是:______.
连接
、
,经测量,
,
,
在
中,由勾股定理可列出关于
的方程:______.解得
______.
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如图2所示,在车轮上取A、B两点,设弧
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
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连接
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在
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【推荐3】如图1是博物馆展出的古代车轮实物,《周礼·考工记》记载:“……故兵车之轮六尺有六寸,田车之轮六尺有三寸……”据此,我们可以通过计算车轮的半径来验证车轮类型,请将以下推理过程补充完整.如图2所示;在车轮上取A,B两点,设
所在圆的圆心为O,半径为
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(1)作弦
的垂线
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______.经测量,
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______
.
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__________.解得
_________
.通过换算,车轮直径约为六尺六寸,可验证此车轮为________之轮.(填“兵车”或“田车”)
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(1)作弦
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(2)在
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真题
【推荐1】如图,在
中,
,
于点
,
于点
,以点
为圆心,
为半径作半圆,交
于点
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![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/11/8bea3413-fbab-4aa9-b0ac-63b9e38fe8d4.png?resizew=156)
(1)求证:
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的切线;
(2)若点
是
的中点,
,求图中阴影部分的面积;
(3)在(2)的条件下,点
是
边上的动点,当
取最小值时,直接写出
的长.
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(1)求证:
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【推荐2】如图,在
中,
,以AC为直径作⊙O交AB于点D,E是BC的中点,连接DE并延长交AC的延长线于点F.
![](https://img.xkw.com/dksih/QBM/2021/4/16/2700950049579008/2701043971866624/STEM/f2379be4-9fce-4c08-8e58-0625dacd9969.png?resizew=224)
(1)求证:DE是⊙O的切线;
(2)若
,
,求⊙O半径的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f8f88798ec42a58dccd212586382b23.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://img.xkw.com/dksih/QBM/2021/4/16/2700950049579008/2701043971866624/STEM/f2379be4-9fce-4c08-8e58-0625dacd9969.png?resizew=224)
(1)求证:DE是⊙O的切线;
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0761165f1176f3a5fe4f7b052832316d.png)
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【推荐2】如图,DE∥BC,且AD=3,AB=5,DE=4,求BC的长.
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