如图所示,已知
,点P是射线AM上一动点(与点A不重合),BC、BD分别平分
和
,分别交射线AM于点C、D,且![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1212f222bed8b39156d13de8a35f40f.png)
(1)求
的度数.
(2)当点P运动时,
与
之间的数量关系是否随之发生变化?若不变化,请写出它们之间的关系,并说明理由;若变化,请写出变化规律.
(3)当点P运动到使
时,求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3b751d36120a1efa42b2f185572397b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3d9cc98e6df306063e645044f0faa7d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2fed9a763c7c81004fde8f4f9693d2f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1212f222bed8b39156d13de8a35f40f.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3818a2c9919d358b4c3713396093822b.png)
(2)当点P运动时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb686e4f5e3938575bc547e849d5513f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/868ff1350bd72625328c85c3097cd85e.png)
(3)当点P运动到使
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e56da880ea1c9760023f70fd0ede58a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
20-21八年级上·山东菏泽·期末 查看更多[5]
山东省菏泽市郓城县2020-2021学年八年级上学期期末数学试题(已下线)易错05 平行线的判定与性质易错-2020-2021学年七年级数学下册期末突破易错挑战满分(北师大版)(已下线)第16讲 几何图形初步 (讲练)-2021年中考数学一轮复习讲练测江苏省盐城市滨海县振东初级中学2021-2022学年七年级下学期数学第一阶段综合练习题内蒙古自治区呼和浩特市赛罕区内蒙古师范大学附属学校2023-2024学年七年级下学期期中数学试题
更新时间:2021-02-04 20:10:46
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相似题推荐
解答题-问答题
|
较难
(0.4)
【推荐1】如图,
,定点E,F分别在直线
,
上,在平行线
、
之间有一动点P,满足
.
满足怎样的数量关系?
解:由于点P是平行线
之间有一动点,因此需要对点P的位置进行分类讨论;如图1,当P点在
的左侧时,
满足数量关系为______________,如图2,当P点在
的右侧时,
满足数量关系为______________.
(2)如图3,
,
分别平分
和
,且点P在
左侧.
①若
,则
_______°.
②猜想
与
的数量关系,并说明理由.
③如图4,若
与
的角平分线交于点
,
与
的角平分线交于点
,
与
的角平分线交于点
,此次类推,则
与
满足怎样的数量关系?(直接写出结果)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/075b213cd00b7b188210392bf06d326e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9070b7c8adf73776c08cdf04e6311cd9.png)
解:由于点P是平行线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5c4cd264c97c1f261229925cc5a6761.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9070b7c8adf73776c08cdf04e6311cd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9070b7c8adf73776c08cdf04e6311cd9.png)
(2)如图3,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf3d566704b44ea4ef1f99c37bd46902.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b8db072e2b6104671b82f948012fb45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd82c51c8a9c1dd494cbb1d9c5411719.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94d5b88cdac96fd5aeb53283673fafe9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dddef81e3af08a62a69bc3e56a940bc2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93591dcef47174fa86cf2a3b8f26ea53.png)
②猜想
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfa70e7c9ef8b856b494d370b7d76482.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6b858c70410f981ca3e22f791585c7e.png)
③如图4,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c20e7f536e1d4be86215aa478f654edd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7d19809b9c7844952c989a6b5dd6733.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a86380a6d6501f6504dcb4aa5e3099f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b02526e9e13f711f789edd185b9c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/417dbe4ac17819ab6e957d88f9f4281e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eae863e7a1f1fed09f1075de4a817c63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7aee84906a02b90b9bd92db0ae6eb27c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dff6bf6a2cc88e622936ac40db7f0fdf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f52b152eaf63415b10ed786a58a2747.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfa70e7c9ef8b856b494d370b7d76482.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c56d6eee97615e5728a6490b8a63bccc.png)
您最近一年使用:0次
解答题-问答题
|
较难
(0.4)
【推荐2】如果两个角的差的绝对值等于
,就称这两个角互为“伙伴角”,其中一个角叫做另一个角的“伙伴角”(本题所有的角都指大于
小于
的角),例如
,
,
,则
和
互为“伙伴角”,即
是
的“伙伴角”,
也是
的“伙伴角”.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/12/90e780bd-e7d4-41bc-b36e-8bd27fc83717.png?resizew=442)
(1)如图1.O为直线
上一点,
,
,则
的“伙伴角”是_______________.
(2)如图2,O为直线
上一点,
,将
绕着点O以每秒
的速度逆时针旋转得
,同时射线
从射线
的位置出发绕点O以每秒
的速度逆时针旋转,当射线
与射线
重合时旋转同时停止,若设旋转时间为t秒,求当t何值时,
与
互为“伙伴角”.
(3)如图3,
,射线
从
的位置出发绕点O顺时针以每秒
的速度旋转,旋转时间为t秒
,射线
平分
,射线
平分
,射线
平分
.问:是否存在t的值使得
与
互为“伙伴角”?若存在,求出t值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/235d495d88b8e51f89e2e4da27328025.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfe639eab78eafd2d40ea70aa5d3f21d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58f859af1ce9e4da521c407411ad0e26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9438830129a138d84b5849acce442e1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d13d64a7d643c170c225883c53089152.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/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d57899ad4774aed9ccc7bd23db72153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d57899ad4774aed9ccc7bd23db72153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/12/90e780bd-e7d4-41bc-b36e-8bd27fc83717.png?resizew=442)
(1)如图1.O为直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fad4140c2e254823a8cc89fff06dcbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/17a285533b962ac3a1bd8dc46e9351a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/418ebb89d29f4f631b055c911e8d178a.png)
(2)如图2,O为直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8f2a3353bbf413a24c461bb7d8d68d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d22df2977de56cc69be0c1e847653d7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a840804ee07144f46c9c2a33e33ae450.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cbee6d5731d6f4bb1e4f2ba3d89b7dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb204f42d5fb6cd55050a18cca2804b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84a02c61cb552d1173b18b42f8d160dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cc16f868ab9f439f8081d6ce9a56ac7.png)
(3)如图3,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fda71562f4f7207ad317e6ce37a8566.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebf79e5246ad8e945c5c1ff1f68007b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc63679c80e6bd24f3a27763d545dcdc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a857e0044303d7d53733147ccc6194ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf3369e0ea90e8d5cf4b6b3c45c0fd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f773ca20bd122f053b3e7b67f048533.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88e9f7d1272b7344346b58b660aa260a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5ec4210f08cfe005b7eaa28eb69fee4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abd13974aebe38eb2a1d744a01ea5aa5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f773ca20bd122f053b3e7b67f048533.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2d446f2e1ede1cb84fe36c8214e0de7.png)
您最近一年使用:0次
解答题-作图题
|
较难
(0.4)
解题方法
【推荐1】已知:
和同一平面内的点
.
(1)如图1,点
在
边上,过
作
交
与
,
交
于
.依题意,在图1中补全图形,并判断
与
的数量关系,并直接写出结论(不需证明).
(2)如图2,点
在
的延长线上,
,
,判断
与
的位置关系,并证明.
(3)如图3,若点
是
外部的一个动点,过
作
交直线
于
,
交直线
于
,试着画一画,然后直接写出
与
的数量关系(不需证明).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
(1)如图1,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46c5f94f49b047f8075bfcd4262f611f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d366d4c2b418f78f3f2d08173388b759.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c962fe4f47732b8e6e83d17ff2b9af13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3818a2c9919d358b4c3713396093822b.png)
(2)如图2,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d366d4c2b418f78f3f2d08173388b759.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4550af14ce0b04bf33f16dd8793ee0dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
(3)如图3,若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46c5f94f49b047f8075bfcd4262f611f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d366d4c2b418f78f3f2d08173388b759.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c962fe4f47732b8e6e83d17ff2b9af13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3818a2c9919d358b4c3713396093822b.png)
![](https://img.xkw.com/dksih/QBM/2020/8/26/2536058190757888/2536383701188608/STEM/1b0f9fa0acae4c498fe6e70795f9f77f.png?resizew=473)
您最近一年使用:0次
解答题-问答题
|
较难
(0.4)
名校
【推荐2】已知:
中,
是
的角平分线,
是
的边上的高,过点B作
,交直线
于点F.
(1)如图,若
,
,则
_______________.
![](https://img.xkw.com/dksih/QBM/2023/1/6/3146901332197376/3148362101858304/STEM/ac9ec85967f84eaaa7d7617e76e90a68.png?resizew=210)
(2)若(1)中的
,
,
_____________.(用
,
表示)
(3)如图,(2)中的结论还成立吗?若成立,说明理由;若不成立,请求出
.(用
,
表示)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4747cb7fddc24b1e92239a884c6f307a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(1)如图,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a858e3fda1505e5aede22f4d6edd3f31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2a427709e6575431882877cda3b59ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae96db8233f7cefc1b38d5ff10845bfe.png)
![](https://img.xkw.com/dksih/QBM/2023/1/6/3146901332197376/3148362101858304/STEM/ac9ec85967f84eaaa7d7617e76e90a68.png?resizew=210)
(2)若(1)中的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/597ce705d3a2fe04d29de9e81ec6250d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9e19f18d1cada47c668e26f4df04d70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae96db8233f7cefc1b38d5ff10845bfe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
(3)如图,(2)中的结论还成立吗?若成立,说明理由;若不成立,请求出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36719f1e764ee0e719b65c49fae84677.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://img.xkw.com/dksih/QBM/2023/1/6/3146901332197376/3148362101858304/STEM/fe2c675d41164a99a5c11d2bae146393.png?resizew=260)
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解答题-问答题
|
较难
(0.4)
【推荐3】长江汛期即将来临,江阴防汛指挥部在一危险地带两岸各安置了一探照灯,便于夜间查看江水及两岸河堤的情况.如图,灯A射线自
顺时针旋转至
便立即回转,灯B射线自
顺时针旋转至
便立即回转,两灯不停交叉照射巡视.若灯A转动的速度是
秒,灯B转动的速度是
秒,且a、b满足
.假定这一带长江两岸河堤是平行的,即
,且
.
(1)求a、b的值;
(2)若灯B射线先转动20秒,灯A射线才开始转动,在灯B射线第一次与
垂直之前,A灯转动几秒,两灯的光束互相平行?
(3)如图,两灯同时转动,在灯A射线到达
之前.若射出的光束交于点C,过C作
交
于点D,则在转动过程中,
与
的数量关系是否发生变化?若不变,请求出其数量关系;若改变,请求出其取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50b3ae183997b707d16eb4e7f6712fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5dc246b7f5f793eb1714a07301de1e9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0abda9f1f26f05c813eb582747e412b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92c178f5cc5c3a07f93c00a10b9639c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7928198bde37727e3a04a7f3e6b306fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3e603d5cbbd35815bbfd2b83574e86f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/7/12f19640-bbf3-4b18-82f7-3fc8a8d08035.png?resizew=469)
(1)求a、b的值;
(2)若灯B射线先转动20秒,灯A射线才开始转动,在灯B射线第一次与
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
(3)如图,两灯同时转动,在灯A射线到达
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50b3ae183997b707d16eb4e7f6712fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bfa14df2e34162f35f421f2ae598cc2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbce11aa19b8bd2bf6ee5a834e005de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/727ad3e630a224303d6d3b8ad5c114ba.png)
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