如图,钱塘江入海口某处河道两岸所在直线(PQ,MN)夹角为20°,在河道两岸安装探照灯B和A,若灯A射线自AM顺时针旋转至AN便立即回转,灯B射线自BQ逆时针旋转至BP便立即回转,两灯不停交叉照射巡视.设灯A转动的速度是a度/秒,灯B转动的速度是b度/秒.已知∠BAN=50°.
(1)当b=2时,问灯B转动几秒后,射出的光束第一次经过灯A?
(2)当a=3,b=6时,若两灯同时转动,在1分钟内(包括1分钟),问A灯转动几秒,两灯的光束互相平行?
(3)若A、B两灯同时转动(a>b),在45秒与90秒时,两灯的光束各平行一次,求a,b的值.
(1)当b=2时,问灯B转动几秒后,射出的光束第一次经过灯A?
(2)当a=3,b=6时,若两灯同时转动,在1分钟内(包括1分钟),问A灯转动几秒,两灯的光束互相平行?
(3)若A、B两灯同时转动(a>b),在45秒与90秒时,两灯的光束各平行一次,求a,b的值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/f55bf334-1555-4468-a8ea-ed32a10483a5.png?resizew=199)
2021九年级·浙江·专题练习 查看更多[3]
(已下线)第16讲 几何图形初步(测)-备战2021年中考数学一轮复习讲练测(浙江)(已下线)【新东方】 义乌初中数学初一下【00024】宁夏石嘴山市平罗县2020-2021学年七年级下学期期末考试数学试题
更新时间:2021-03-17 18:35:07
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【推荐1】如图,点A从点
开始以每秒
个单位长度的速度在射线
上向右匀速运动,同时点
从点
出发,向右上方运动,并在点C处与点A重合,重合后,点A运动方式不变,点B沿线段
:
向右下方运动,并在点
处,改变运动方向沿线段
:
向右上方运动,直到当点B到达点E时,两个点同时停止运动.在运动过程中,点B与点A的横坐标总保持相等,设运动时间为t秒.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/2/e3bf9faf-68d4-4ea4-a1a1-4ab32be36c90.png?resizew=207)
(1)当点A,B重合于点C时,求t的值.
(2)求
段所在直线的函数表达式,并求
时点B的坐标;
(3)直接写出A,B之间的距离不超过3时t的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb5f2f27d501eff7f0b8ac58ba390213.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4b8503f4706b8321e4e79a87eadea84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3171b3d11c6f4619e189677345357508.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1089a572469bcd8ce70bc0d2e2e24833.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e53620f1591c672eeed905ada620c74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cc04e392ce536a30fe29b233ff866d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9460285764a02e5ef8b9998a3bc60a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4402b3abc9825c193e58d1b1ebd9fe8c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/2/e3bf9faf-68d4-4ea4-a1a1-4ab32be36c90.png?resizew=207)
(1)当点A,B重合于点C时,求t的值.
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a15a13b4190ac3d5feaee27a4c97b21b.png)
(3)直接写出A,B之间的距离不超过3时t的取值范围.
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【推荐2】综合与实践:
阅读:
,它在数轴上的意义为:表示5的点与原点(即表示0的点)之间的距离为5;
,它在数轴上的意义为:表示5的点与表示2的点之间的距离为3;
它在数轴上的意义为:表示5的点与表示
的点之间的距离为7.
理解:(1)
,它在数轴上的意义为表示______的点与表示______的点之间的距离为
;
(2)
,它在数轴上的意义为表示______的点与表示______的点之间的距离为
;
归纳:(3)已知有理数
,
,则
在数轴上的意义为______;
应用:(4)点
,
,
在数轴上分别表示有理数
,
,1,回答下列问题:
①点
到点
的距离为______;点
到点
的距离可表示为______(用含
的式子表示);
②
在数轴上的意义为______;若
,则满足条件的
的值为_____.
阅读:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23d80648260f8cdb53eb25a3e0f6b8b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ac960734bba8815c6291f2d09a9bb37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93f15d02c6a096962d7e35ba2b411fba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274a9dc37509f01c2606fb3086a46f4f.png)
理解:(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e056b0d549641675e31ecbfe63407c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a41354372ccb7c514380a0b70d97aa08.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f39821d70ec89dcf3f205dd11c892897.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4b8503f4706b8321e4e79a87eadea84.png)
归纳:(3)已知有理数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a13880b9454c5942f164d934b1834783.png)
应用:(4)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.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/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01317332a203c898536b1d0459f51d23.png)
①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/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbfd5625b12ce2fdeff7bda0250fc626.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b3c87ee8268ae2347d2829d04895586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
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名校
【推荐3】已知
是最小的正整数,
是
的相反数,
,且
、
、
分别是点
、
、
在数轴上对应的数.动点
从点
出发沿数轴正方向匀速运动,动点
同时从点
出发也沿数轴正方向匀速运动,点
的速度是每秒2个单位长度,点
的速度是每秒1个单位长度,设点P的运动时间为t秒.
(1)
= ,
= ,
= ;
(2)当t=1时,线段PQ长为 ;
(3)若
、
出发的同时,动点
从点
出发沿数轴正方向匀速运动,速度为每秒4个单位长度.当点
追上点
后,点M立即按原速度沿数轴负方向匀速运动,求点
追上点Q后,再运动几秒,
到
的距离等于
到
的距离?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a94acdfb41489d5694b5a64b9e99754.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcb168800047d929b98cc4d60df490fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.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/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
(2)当t=1时,线段PQ长为 ;
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/3/5a7aefe7-c33d-4d21-ad31-9f951ccd412f.png?resizew=500)
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【推荐1】“一带一路”让中国和世界更紧密,“中欧铁路”为了安全起见在某段铁路两旁安置了A,D两座可旋转探照灯.假定主道路是平行的,即
,
,
为
上两点,
平分
交
于点
,
为
上一点,连接
,
平分
交
于点
.
(1)若
,则
;
(2)作
交
于点
,且满足
,当
时,试说明:
;
(3)在(1)问的条件下,探照灯A、D照出的光线在铁路所在平面旋转,探照灯射出的光线
以每秒5度的速度逆时针转动,探照灯
射出的光线
以每秒15度的速度逆时针转动,
转至射线
后立即以相同速度回转,若它们同时开始转动,设转动时间为
秒,当
回到出发时的位置时同时停止转动,则在转动过程中,当
与
互相平行或垂直时,请直接写出此时t的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c412414cd0ad5460ba33acf319baf12.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21b28f28ced0531d1df34fcf04c6c67f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167d31eb8432b5c0364316e5048c23dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2947ca8e0cdbeb4aab80ce9e7b63ba98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/6/c869d51c-05a3-488c-9829-e9dd39a5ec7f.png?resizew=197)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8a896e05730e8dd3bee64a4911c33dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c71bae6b035958ccae00082e35b1fae9.png)
(2)作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a7e4a6765ce78b05ee97764771e01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b226c4ed387f8dd2b2bf77040c1b2ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1cb4ea95b3dffec0dac3247a50296984.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b43be568ae5186900cfb39484a3c9301.png)
(3)在(1)问的条件下,探照灯A、D照出的光线在铁路所在平面旋转,探照灯射出的光线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3533837e3d08c461dea031a44e5424d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3533837e3d08c461dea031a44e5424d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3533837e3d08c461dea031a44e5424d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3533837e3d08c461dea031a44e5424d.png)
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【推荐2】(1)若组成
和
的两条边互相平行,且
是
的2倍小
,求
的度数.
(2)如图,放置在水平操场上的篮球架的横梁
始终平行于
与上拉杆
形成的
,主柱
垂直于地面,通过调整
和后拉杆
的位置来调整篮筐的高度.当
时,点H,D,B在同一直线上,求
的度数.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/a68bba5a-d429-43fc-8968-8a47903dc721.png?resizew=126)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d57899ad4774aed9ccc7bd23db72153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d57899ad4774aed9ccc7bd23db72153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76c12e76fbd84eeec721386bd3b04cc4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
(2)如图,放置在水平操场上的篮球架的横梁
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2fbb88b8b4f62188428cb240291963c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/989aac4f5de9570545c7d83618b84ec6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
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