已知圆
直线
.
(1)圆
的圆心到直线
的距离为?
(2)圆上
任意一点
到直线
的距离小于
的概率为多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04019c89a110e5e83d6b1ed8db52aeca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16cdee4af98807016c1e4eb7c2f84748.png)
(1)圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
(2)圆上
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
更新时间:2018-03-23 15:32:55
|
相似题推荐
解答题-问答题
|
适中
(0.65)
名校
【推荐1】(1)写出点
到直线
的距离公式并证明.
(2)证明:点
到直线
的距离
恒小于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7775aa57ca0e62216f3039ed88dceed0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6b6e44dd054b54f89e7c237eb1428da.png)
(2)证明:点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bdfc750fe0ace842a461e89f2b7b290.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9528b4f5ceeae21a3f102ba37047b793.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e2031d209711b058f3d278ede3c1d33.png)
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解答题-问答题
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解题方法
【推荐1】如图,在平面直角坐标系
中,已知定点
,
,动点
到点
的距离不小于 点
到点
距离的2倍.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/22/cb86211a-bc95-4c81-86a6-4374201828a3.png?resizew=169)
(1)求动点
的轨迹所在的平面区域
的面积
;
(2)由点
随机地向下方作一条射线
,求这条射线
经过平面区域
的概率.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f497282b2f0c81360be623c9df436992.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32366143230ca122894a4bada7c7b96d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49cba284d675a3028d7a8d54f1f8ae70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d259822ab64b8626f3893b8432673358.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/22/cb86211a-bc95-4c81-86a6-4374201828a3.png?resizew=169)
(1)求动点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cb9ad1e34877b0db02d0219332b0f7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
(2)由点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cb9ad1e34877b0db02d0219332b0f7b.png)
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解答题-证明题
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解题方法
【推荐2】某大型超市拟对店庆当天购物满
元的顾客进行回馈奖励.规定:顾客转动十二等分且质地均匀的圆形转盘(如图),待转盘停止转动时,若指针指向扇形区域,则顾客可领取此区域对应面额(单位:元)的超市代金券.假设转盘每次转动的结果互不影响.
(Ⅰ)若
,求顾客转动一次转盘获得
元代金券的概率;
(Ⅱ)某顾客可以连续转动两次转盘并获得相应奖励,当
时,求该顾客第一次获得代金券的面额不低于第二次获得代金券的面额的概率;
(Ⅲ)记顾客每次转动转盘获得代金券的面额为
,当
取何值时,
的方差最小?
![](https://img.xkw.com/dksih/QBM/2017/11/14/1817064720875520/1818519677378560/STEM/025025e1c2cc466e80fe758076038b13.png?resizew=120)
(结论不要求证明)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4970a85351686c6434730b4985ff3dc7.png)
(Ⅰ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/973c43ce93f409411266f8c1d2b41cc1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8705db804c79b661adba7da15cb31f8c.png)
(Ⅱ)某顾客可以连续转动两次转盘并获得相应奖励,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73eb2f3398f6f7efe3c7a737d19f4fae.png)
(Ⅲ)记顾客每次转动转盘获得代金券的面额为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5cbf1211335bcbc0ebb05414669eda0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://img.xkw.com/dksih/QBM/2017/11/14/1817064720875520/1818519677378560/STEM/025025e1c2cc466e80fe758076038b13.png?resizew=120)
(结论不要求证明)
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解答题-应用题
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【推荐3】某商场为吸引顾客消费推出一项优惠活动.活动规则如下:消费额每满100元可转动如图所示的转盘一次(指针停在任一位置的可能性相等),并获得相应金额的返券.若指针停在A区域返券60元;停在B区域返券30元;停在C区域不返券.例如:消费268元,可转动转盘2次,所获得的返券金额是两次金额之和.
(1)若某位顾客消费128元,求返券金额不低于30元的概率;
(2)若某位顾客恰好消费280元,并按规则参与了活动,他获得返券的金额记为X(元).求随机变量X的分布列和数学期望.
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