如图,已知AC是⊙O的直径,B为⊙O上一点,D为
的中点,过D作EF∥BC交AB的延长线于点E,交AC的延长线于点F.
(Ⅰ)求证:EF为⊙O的切线;
(Ⅱ)若AB=2,∠BDC=2∠A,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed41d321f4c0717ac5b443aad942d9a7.png)
(Ⅰ)求证:EF为⊙O的切线;
(Ⅱ)若AB=2,∠BDC=2∠A,求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed41d321f4c0717ac5b443aad942d9a7.png)
![](https://img.xkw.com/dksih/QBM/2019/2/27/2149667136643072/2150555986542592/STEM/7e38c79eb23046dbbc78cae2523723b4.png?resizew=150)
更新时间:2018-08-28 13:17:45
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相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图,
是等边三角形,D、E分别是的边
上的点,且
,
与
相交于点P,
于点F.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/19/6488695d-0c8f-4605-9340-f6a7a0862372.png?resizew=144)
(1)求证:
;
(2)求
的度数;
(3)若
,
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8ed1fce01430ae31294c29d626626f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d42218a68301d770accaaefb96b19f8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb91cb9a5a14169845d700fbd95890ac.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/19/6488695d-0c8f-4605-9340-f6a7a0862372.png?resizew=144)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3eac6f98ed81727dc5f6699ea5117fff.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42fa5dff377ef08e416547def489def0.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e410f25977e460b14e0512c2dd348e1c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bec03e804f0cea1db5cde2aa185056a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
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【推荐2】如图,矩形
的两条对角线相交于点O,
,
,求矩形的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc1eb76fe74cba30f7cbcde349ba80da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c922b145ddd3eca237c83d6b287cf3ce.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/27/1c2b7c55-cd53-425b-9bca-895ec3cb5d86.png?resizew=169)
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【推荐1】如图,AB为⊙O的直径,弦CD垂直平分OB于点E,点F在AB延长线上,∠AFC=30°.
(1)求证:CF为⊙O的切线.
(2)若半径ON⊥AD于点M,CE=
,求图中阴影部分的面积.
(1)求证:CF为⊙O的切线.
(2)若半径ON⊥AD于点M,CE=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/2/1ff0d574-f759-4585-bca5-118439761568.png?resizew=179)
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【推荐2】如图,已知D为
上一点,点C在直径
的延长线上,
与
相切,交
的延长线于点E,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/30/10ddacb0-c831-4362-b5c9-795c79e1bbd7.png?resizew=160)
(1)判断
与
的位置关系,并说明理由;
(2)若
,
,求
的半径;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
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(1)判断
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8a7b5adfcac0f46a4cd19da4ebb4a2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bb3aeb227e9a9d25bcb7f6d803d2d11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
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【推荐1】如图,四边形
内接于
,
是
的直径,过点C作
的垂线,交
的延长线于点E,连接
.
![](https://img.xkw.com/dksih/QBM/2023/1/2/3144252030656512/3145754564878336/STEM/e9e4f9b2975f4015a0cb013023d13fe3.png?resizew=142)
(1)若
平分
,求证:
是
的切线;
(2)若
是
的切线,
,求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
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![](https://img.xkw.com/dksih/QBM/2023/1/2/3144252030656512/3145754564878336/STEM/e9e4f9b2975f4015a0cb013023d13fe3.png?resizew=142)
(1)若
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2947ca8e0cdbeb4aab80ce9e7b63ba98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fc56c77464a17a1e97b568762a3e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fc56c77464a17a1e97b568762a3e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bd35f055165577f901117038a8cc609.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdb8eca20ce2c918ea4034ea15210c7f.png)
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【推荐2】如图,四边形ABCD内接于圆,AD,BC的延长线交于点E,F是BD延长线上任意一点,AB=AC.
(1)求证:DE平分∠CDF;
(2)求证:∠ACD=∠AEB.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/30/1f6b783b-7700-46eb-95cf-3bc03254ce82.png?resizew=211)
(1)求证:DE平分∠CDF;
(2)求证:∠ACD=∠AEB.
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【推荐1】如图,已知
是
的直径,点P在
的延长线上,弦
平分
,且
于点D.
(1)求证:
是
的切线.
(2)若
cm,
cm,求弧
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e98f2e85bdf9c6669c14f8966ed53be.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/8/e2d29cc1-0d99-4f13-a8ce-1883ff7a5b79.png?resizew=182)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54275b7e571660d0a9e0370fbfe5050b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/454328a8e75953fdb0835ce80d9566e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
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【推荐2】沈括的《梦溪笔谈》是中国古代科技杰作,其中它收录了计算圆弧长度的“会圆术”.如图,
是以点
为圆心,
为半径的圆弧,
是
的中点,
于点
.“会圆术”给出
的弧长近似值
的计算公式:
.已知
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/3/44049046-dfc3-4537-a05d-a7763b707639.png?resizew=137)
(1)求
的值;
(2)记实际弧长为
,求
的值约为多少?(结果保留两位小数,参考数据
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16d65cecaf8a3dc2953f4109c75a981e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16d65cecaf8a3dc2953f4109c75a981e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/490d9fe6afdb118ef20f23d3cfc9fdfc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16d65cecaf8a3dc2953f4109c75a981e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5873c01192b7d33b7483f444f90b5b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ad98c56b031199d83698eefb2d1991b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6e3dfcd8aff269dd5aba398816490c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc1eb76fe74cba30f7cbcde349ba80da.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/3/44049046-dfc3-4537-a05d-a7763b707639.png?resizew=137)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5873c01192b7d33b7483f444f90b5b0.png)
(2)记实际弧长为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b162f568534c85f5af97a33a6c94238.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/460317e7c26f95b9b29cfe1a89b796d6.png)
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