如图1,某玩具风车的支撑杆
垂直于桌面
,点
为风车中心,
,风车在风吹动下绕着中心
旋转,叶片端点
,
,
,
将
四等分,已知
的半径为
.
时,点
在
左侧,如图2所示,求点
到桌面
的距离(结果保留根号);
(2)在风车转动一周的过程中,求点
到桌面的距离不超过
时,点
所经过的路径长(结果保留
);
(3)连接
,当
与
相切时,求切线长
的值,并直接写出
,
两点到桌面
的距离的差.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3789307bad619f9c7c3873c0b7282a85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.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/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdb26c5cdef6f16f4b39cd091041b439.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/245f13cffbddce02a1f6d18854ce8664.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
(2)在风车转动一周的过程中,求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2a835d77c364303ea59d96e6ce42a58.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
(3)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
2024·河北石家庄·一模 查看更多[3]
2024年河北省石家庄长安区中考一模数学试题(已下线)抢分通关07 锐角三角函数解决实际问题(2易错7题型)-备战2024年中考数学抢分秘籍(全国通用)(已下线)抢分秘籍10 圆中证切线、求弧长、求面积、新定义探究问题(压轴通关8题型)-备战2024年中考数学抢分秘籍(全国通用)
更新时间:2024-03-31 21:16:25
|
相似题推荐
解答题-证明题
|
较难
(0.4)
解题方法
【推荐1】在
ABC和
CDE中,∠ACB=∠DCE=90°,AC=BC,CD=CE,点D在边AC上,点E在边BC上,如图1将
CDE绕点C按顺时针方向旋转,旋转角为α(0°<α≤90°).
![](https://img.xkw.com/dksih/QBM/2021/8/12/2784346406617088/2802319805521920/STEM/9c4ace2559c74293991c86f41ca89e6e.png?resizew=456)
(1)连接AD,BE.求证:AD=BE,AD⊥BE;
(2)当旋转至图2位置时,点A,D,E在一条直线上,连接BD,BE,若AD=2
,CD=1,则BD= ;
(3)当α=90°时,如图3,连接AD,BE,延长AD交BE于点F,连接CF,若DF=1.EF=
.则CF= .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce4cba95fc7d4853a243f8e3fb20ce70.png)
![](https://img.xkw.com/dksih/QBM/2021/8/12/2784346406617088/2802319805521920/STEM/9c4ace2559c74293991c86f41ca89e6e.png?resizew=456)
(1)连接AD,BE.求证:AD=BE,AD⊥BE;
(2)当旋转至图2位置时,点A,D,E在一条直线上,连接BD,BE,若AD=2
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
(3)当α=90°时,如图3,连接AD,BE,延长AD交BE于点F,连接CF,若DF=1.EF=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
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解题方法
【推荐2】如图1,在平面直角坐标系中,点A坐标为(2,0),点B在x轴负半轴上,C在y轴正半轴上,∠ACB=90°,∠ABC=30°.
(1)求点B坐标;
(2)如图2,点P从B出发,沿线段BC运动,点P运动速度为每秒2个单位长度,设运动时间为t秒,用含t的式子表示三角形△OBP的面积S;
(3)如图3,在(2)的条件下,点P出发的同时,点Q从O出发,在线段OC上运动,运动速度为每秒2个单位长度,一个点到达终点,另一个点也停止运动.连接PQ,以PQ为一边,在第二象限作等边△PQM,作ME⊥y轴于E,点D为PC中点,作DN⊥BC交y轴于N,若CE=BP,BC=4
,求N的坐标.
(1)求点B坐标;
(2)如图2,点P从B出发,沿线段BC运动,点P运动速度为每秒2个单位长度,设运动时间为t秒,用含t的式子表示三角形△OBP的面积S;
(3)如图3,在(2)的条件下,点P出发的同时,点Q从O出发,在线段OC上运动,运动速度为每秒2个单位长度,一个点到达终点,另一个点也停止运动.连接PQ,以PQ为一边,在第二象限作等边△PQM,作ME⊥y轴于E,点D为PC中点,作DN⊥BC交y轴于N,若CE=BP,BC=4
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/26/bc7a7b5c-d3a1-430d-bea2-a1e48d4d231a.png?resizew=308)
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【推荐1】如图,
为
直径,
为切线,
为圆上一点,连接
交
于点
,交
于点
,连接
,且
.
(1)若
,求
的度数;
(2)连接
,求证:
;
(3)若
,求
.
![](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/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fc56c77464a17a1e97b568762a3e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60b90ca31eb093c3a5dd8e7408343ec7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a16dc02090b6e9263555061f14fbc8c.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0e8f35e8fff37c26b396c5a3dfdea4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/febc9a89d0d1c97b88c0f4acd32b4e67.png)
(2)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43cced3c9805ded932d6e9455a94c323.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cab0697ba2b17b3918279ad7febcfc1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57c46cf4027b6772ed73816e51b82bac.png)
![](https://img.xkw.com/dksih/QBM/2021/4/29/2710014036738048/2715960213782528/STEM/58d4ccb4-cb02-4539-b580-26bd1df1d117.png)
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【推荐2】问题发现:
是半径为2的
上一点,直线
是圆
外一条直线,
于点
,圆心
到直线
的距离为3,则线段
的最小值为______;
问题探究:
(2)如图2,在
中,
,
,
,点
是
边上一动点且满足
,点
是
的中点,当点
在
运动时,求
面积的最小值.
问题解决:
(3)如图3,有一边长为20米的菱形参观展览区
,点
为
的中点,点
是
上一点,
,根据实际情况,需要在
右侧建造一个与
对称的茶歇区
,点
的对应点为
,连接
交
于
,连接
,展方为了增加展区的总体收益,欲在茶歇区斜对面位置内出售高品质茶具,决定在
上选取一点
,使
,划定
为茶具售卖区,已知茶具售卖区每平方米
元,问该售卖区最少需要多少元?(
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9c50360563e2a58800af3a9cf7d9652.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
问题探究:
(2)如图2,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60d9142db4dd2ef151bf3d4a63afb61e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f54cfc1c15c0361cf5b81c03640faede.png)
![](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/377b5f7197e5bd1afeea4d931307956a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](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/36691f0269294ecae8f00b7bce97756c.png)
问题解决:
(3)如图3,有一边长为20米的菱形参观展览区
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.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/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/284e282bb1d9fbf8634b3506ee5358ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f2ea13010e2399194be2a681310543e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eadb6f330e2d5325adb08c2b1d80b1ae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fd17a66a2af938c89e46f22e4d893b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fd17a66a2af938c89e46f22e4d893b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/865c9e604abc386f4a61c1dc1ba24466.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5090091503f9c176630ba736fd42e67c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b685c556cc423e4833c1dc671a134cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/460317e7c26f95b9b29cfe1a89b796d6.png)
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名校
【推荐1】如图
某种三角形台历被放置在水平桌面上,其左视图如图
,其中点
是台历支架
、
的交点,同时又是台历顶端连接日历的螺旋线圈所在圆的圆心.现测得
,
,
.
求点
到直线
的距离;
求张角
的大小;
现把某月的日历从台历支架正面翻到背面(即
与
重合),求点
所经历的路径长.
(参考数据:
,
,
,
,
取
,所有结果精确到
,可使用科学计算器)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5b2a8c80bc574fc27cb32dcb06c6679.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdeb81be9e93f2222b96c8297aaef394.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ed69ca4e533e51efcf328c7085334b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95329b4a34e51ab0bbf0220e63bfc539.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f94329441d810e832a4fcfefa6b7db7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e6a6af953b91ca844251e4b7ee843ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4141b26d2c32655003494a91ad6331b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5b2a8c80bc574fc27cb32dcb06c6679.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbf6101c529b7868bc1c2fd46aca16bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65863c1abad833b79c303bfca24f535c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56b5ab330e9b7a07c526fbdd861fb1ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4bb89a362c1faf4d0c306eabbb59710.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ed69ca4e533e51efcf328c7085334b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdeb81be9e93f2222b96c8297aaef394.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c14c6709d2a04863cacdee618b20613e.png)
(参考数据:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2a5881ecd8bdf3022db3feec55caeae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/380184169af2c803484d893d9330b0ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ad326b78d539369ecec0edf31ac8498.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7322acbf862f130df226e34de2d3382e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed2d1ecae9c649cc3c89f9ce0c063208.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8c90ce004f64043218ca670e89503ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff4b3ee8ff8718d3702046240fb7810f.png)
![](https://img.xkw.com/dksih/QBM/2018/9/29/2042894449999872/2044298507968512/STEM/11856888d35e46c1bbc2ec07bff11369.png?resizew=226)
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【推荐2】等边三角形
的边长为
,在
,
边上各有一个动点E,F,满足
,连接
,
相交于点P.
(1)
的度数;
(2)当E从点A运动到点C时,试求点P经过的路径长;
(3)连接
,直接写出
长度的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38387ba1cadfd3dfc4dea4ca9f613cea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8ce1475f537b4ad21775bfaa16daa0c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/24/b90c36a8-ea8a-4ce3-aa2d-eee41340bfb1.png?resizew=167)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb686e4f5e3938575bc547e849d5513f.png)
(2)当E从点A运动到点C时,试求点P经过的路径长;
(3)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a253c7fdf589ee3dece13d5b5b5732.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a253c7fdf589ee3dece13d5b5b5732.png)
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真题
【推荐3】阅读理解:
我们把满足某种条件的所有点所组成的图形,叫做符合这个条件的点的轨迹.
例如:角的平分线是到角的两边距离相等的点的轨迹.
问题:如图1,已知EF为△ABC的中位线,M是边BC上一动点,连接AM交EF于点P,那么动点P为线段AM中点.
理由:∵线段EF为△ABC的中位线,∴EF∥BC,
由平行线分线段成比例得:动点P为线段AM中点.
由此你得到动点P的运动轨迹是: .
知识应用:
如图2,已知EF为等边△ABC边AB、AC上的动点,连结EF;若AF=BE,且等边△ABC的边长为8,求线段EF中点Q的运动轨迹的长.
拓展提高:
如图3,P为线段AB上一动点(点P不与点A、B重合),在线段AB的同侧分别作等边△APC和等边△PBD,连结AD、BC,交点为Q.
(1)求∠AQB的度数;
(2)若AB=6,求动点Q运动轨迹的长.
我们把满足某种条件的所有点所组成的图形,叫做符合这个条件的点的轨迹.
例如:角的平分线是到角的两边距离相等的点的轨迹.
问题:如图1,已知EF为△ABC的中位线,M是边BC上一动点,连接AM交EF于点P,那么动点P为线段AM中点.
理由:∵线段EF为△ABC的中位线,∴EF∥BC,
由平行线分线段成比例得:动点P为线段AM中点.
由此你得到动点P的运动轨迹是: .
知识应用:
如图2,已知EF为等边△ABC边AB、AC上的动点,连结EF;若AF=BE,且等边△ABC的边长为8,求线段EF中点Q的运动轨迹的长.
拓展提高:
如图3,P为线段AB上一动点(点P不与点A、B重合),在线段AB的同侧分别作等边△APC和等边△PBD,连结AD、BC,交点为Q.
(1)求∠AQB的度数;
(2)若AB=6,求动点Q运动轨迹的长.
![](https://img.xkw.com/dksih/QBM/2016/10/14/1574248060592128/1574248067022848/STEM/0105862bceb344bc8386e739bf909eaf.png)
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【推荐1】地球有多大?
多年前,古希腊数学家埃拉托斯特尼(
)利用太阳光线测量出了地球子午线的周长.下面让我们一起开启“探求地球周长”的数学项目化学习之旅.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4abb59695562b3a1295a251dc97da700.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa99befeccfed858c97fc54ea77038f.png)
项目任务 (一) | 如图1,某日正午,小红在B地(与太阳直射点A在同一子午线上)测得太阳光与木棍的夹角为![]() ![]() ![]() ![]() |
项目任务 (二) | 如图2,某日正午,小红和小明在同一子午线的B地、C地测得太阳光与木棍的夹角分别为![]() ![]() ![]() ![]() ![]() ![]() |
项目任务 (三) | 如图3,日落时,身高为h的小亮趴在地上平视远方,在太阳完全从地平线上消失的一瞬间,按下秒表开始计时.同时马上站起来,当太阳再次完全消失在地平线的瞬间,停止计时,小亮利用这个时间差和地球自转的速度计算出了![]() ![]() |
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【推荐2】某课外兴趣小组设计了一个长方形时钟钟面,此长方形框的宽为
,时钟的中心在长方形对角线的交点上,数字
在长方形的顶点上,数字
、
、
、
标在所在边的中点上,如图所示.
![](https://img.xkw.com/dksih/QBM/2019/12/16/2356430033895424/2356458204061696/STEM/b87f8b1ee66f4d0f8461d3a093d8ac01.png?resizew=142)
(1)当时针指向数字
时,时针与分针的夹角是多少度?
(2)请你在长方形框上标出数字
的位置,并说明确定该位置的方法.
(3)请你在长方形框上标出钟面上其余数字的位置,并写出相应的数字.(要画出反映解题 思路的辅助线)
(4)长方形的长应为多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9ca2362e1dbf9a05e821fb5880f93b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8d02ea8c4988c5c28ab93f0d70fb55a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8da45c443af7994a26ffa9d8894e7262.png)
![](https://img.xkw.com/dksih/QBM/2019/12/16/2356430033895424/2356458204061696/STEM/b87f8b1ee66f4d0f8461d3a093d8ac01.png?resizew=142)
(1)当时针指向数字
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
(2)请你在长方形框上标出数字
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
(3)请你在长方形框上标出钟面上其余数字的位置,并写出相应的数字.(要画出反映解题 思路的辅助线)
(4)长方形的长应为多少?
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