目前,各大城市都在积极推进公共自行车建设,努力为人们绿色出行带来方便,图(1)所示的是一辆自行车的实物图.图(2)是自行车的车架示意图,
,
,
,
于点E,座杆
的长为
,点A,E,C,F在同一直线上,且
,公共自行车车轮的半径约为
,且
与地面平行.
![](https://img.xkw.com/dksih/QBM/2021/6/2/2734460045082624/2734883109601280/STEM/94f9b0faab8b46e68cf9fc090940872d.png?resizew=381)
(1)求车架中
的长;
(2)求车座点F到地面的距离.(结果精确到
,参考数据:
,
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e8f9537960ba8f0acd4f9ee23822c5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53953bd294f581754fa4878a5bc5b6f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/743e78238b6e16b5574b46ebff840430.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68fbbd17c89f03dbb61cd6ffdb9a0344.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3668a3f3ce5b8a272ad92c2ebd233f5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7142383d6de5773d8be46e6f98cb4ac0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d73f6eb456829de6bfed5b65c7232435.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/2021/6/2/2734460045082624/2734883109601280/STEM/94f9b0faab8b46e68cf9fc090940872d.png?resizew=381)
(1)求车架中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
(2)求车座点F到地面的距离.(结果精确到
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84a3d448d4e52782ca2024411c5a11fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42ecf1ef8d629f08050be24cd79b9abe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50922f69519376f0655cc9db737d32c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/688e008ebc2091f23e4e8ebb18a30486.png)
20-21九年级下·浙江·期末 查看更多[1]
(已下线)【新东方】 【2021.5.25】【NB】【初三下】【数学】【NB00037】
更新时间:2021-06-03 09:16:50
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相似题推荐
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【推荐1】【项目式学习】
项目主题:设计落地窗的遮阳篷
项目背景:小明家的窗户朝南,窗户的高度
,为了遮挡太阳光,小明做了以下遮阳蓬
的设计方案,请根据不同设计方案完成以下任务.
方案1:直角形遮阳篷
如图1,小明设计的第一个方案为直角形遮阳篷
,点 C 在
的延长线上![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bfa14df2e34162f35f421f2ae598cc2.png)
,
,则支撑杆
m.
(2)小明发现上述方案不能很好发挥遮阳作用,如图2,他观察到此地一年中的正午时刻,太阳光与地平面的最小夹角为a,最大夹角为β.小明查阅资料,计算出
,
,为了让遮阳篷既能最大限度地使冬天温暖的阳光射入室内(太阳光与
平行),又能最大限度地遮挡夏天炎热的阳光(太阳光与
平行).请求出图2中
的长度.
(3)如图3,为了美观及实用性,小明在(2)的基础上将
边改为抛物线形可伸缩的遮阳篷,点F为抛物线的顶点,
段可伸缩),且
,
,
的长保持不变.若以C 为原点,
方向为x 轴,
方向为y 轴.
①求该二次函数的表达式.
②若某时刻太阳光与水平地面夹角
的正切值
使阳光最大限度地射入室内,求遮阳蓬点 D上升的高度最小值(即点
到
的距离)
项目主题:设计落地窗的遮阳篷
项目背景:小明家的窗户朝南,窗户的高度
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/123071570a0cf22f09e563aadb6a874b.png)
的设计方案,请根据不同设计方案完成以下任务.
方案1:直角形遮阳篷
如图1,小明设计的第一个方案为直角形遮阳篷
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bfa14df2e34162f35f421f2ae598cc2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9706fe540d881f6049a4965b5311717b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf6d29649ca983107243a631e087205e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c978d92edf0c4c1ef8620c17df75d35e.png)
(2)小明发现上述方案不能很好发挥遮阳作用,如图2,他观察到此地一年中的正午时刻,太阳光与地平面的最小夹角为a,最大夹角为β.小明查阅资料,计算出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f5c67c39a457feefad1ae839e2a99df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2adb91c4eea578ed8f41b438200682d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/481e426224c3a3ce9bb5a731eed81c40.png)
(3)如图3,为了美观及实用性,小明在(2)的基础上将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/706725f00d4399ac392ac0ee231a4dae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
①求该二次函数的表达式.
②若某时刻太阳光与水平地面夹角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8621b7fe0bb46b5ee2f4cf3cced18f33.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5b3bd5e6bc2a0a277d279bb01af9584.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
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【推荐2】设点
、点
,分别以O、A为圆心,半径为2r、r作圆,两圆在第一象限的交点为P.
![](https://img.xkw.com/dksih/QBM/2022/12/13/3130003836002304/3142089106882560/STEM/718676721b9f4dd2a924324e619256b4.png?resizew=180)
(1)当
时,求点P的坐标;
(2)当
时,能否找到一定点Q,使
为定值?若能找到,请求出Q点的坐标及定值;若不能找到,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c432be73ca47930da14921ecd860ba67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bca1e8963e446793d61fcac47daaa016.png)
![](https://img.xkw.com/dksih/QBM/2022/12/13/3130003836002304/3142089106882560/STEM/718676721b9f4dd2a924324e619256b4.png?resizew=180)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7551011cfb75b26f35b07d6617c6a18b.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69287b2ceabc00af962150998f48fd5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
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【推荐1】如图,
是某景区一段坡度
的上坡路段,
为竖直(与水平面垂直)的监控立杆,点D处安装了摄像头,点A、B分别为摄像头的测速起点与终点.安装调试摄像头时,在摄像头D处测得点A的俯角为
,点B的俯角为
.已知
米,点O、A、B、C、D、E、在同一平面内.
(1)求杆
的高度;(精确到个位)
(2)一辆小汽车从A点驶向B点,摄像头两次测速抓拍的时间间隔为
秒.若
,此路段的限速是40千米/小时,试判断这辆小汽车是否超速违章,并说明理由.(参考数据:
,
,
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/735a99c2e8e7ee40d8c7d95925cb1a06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9eeefe320beb4177905605c72e963e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79a97bb4dcfab4ec7539bc783d563c49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6137b700813150a42d9e728c7cc99ee8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/12/39b0cec6-cf85-44f1-a467-59ea3c8755a1.png?resizew=188)
(1)求杆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
(2)一辆小汽车从A点驶向B点,摄像头两次测速抓拍的时间间隔为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29be23f689eb01e57963495377501257.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d65639672f444b3d4dc6fc4f357ddbd5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fcde7c5584f2f622304b42c87f74d48.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6765ee9c7a9aceffb18378f305f1e7c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ab7252e3adab7ba6e75c02a0ba2af6f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c894b7d6baa55c80c64e74748dad898.png)
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名校
【推荐2】如图,某水产养殖户开发一个三角形状的养殖区域,A、B、C三点的位置如图所示.已知∠CAB=105°,∠B=45°,AB=100
米.(参考数据:
≈1.41,
≈1.73,sin20°≈0.34,cos20°≈0.94,tan20°≈0.36,结果保留整数)
(1)求养殖区域△ABC的面积;
(2)养殖户计划在边BC上选一点D,修建垂钓栈道AD,测得∠CAD=40°,求垂钓栈道AD的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/15/761e2da9-b399-4a2d-873b-75171df4028e.png?resizew=180)
(1)求养殖区域△ABC的面积;
(2)养殖户计划在边BC上选一点D,修建垂钓栈道AD,测得∠CAD=40°,求垂钓栈道AD的长.
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【推荐3】手机软件Smart Measure(智能测量)是一款非常有创意且实用性很高的数码测距工具.它可以利用手机上的摄像头和距离传感器来测量目标的距离、高度、宽度、角度和面积.测量过程非常简单;如图1、图2,打开软件后先将手机摄像头对准物体的底部按测量键,保持相同姿势,再把手机相机镜头对准测量物体的顶端按测量键,最后按下“大树键”即可测量出物体的高度智能软件的运行离不开数学原理.
![](https://img.xkw.com/dksih/QBM/2021/1/26/2644603077525504/2676292530724864/STEM/50214c81-5e88-4b80-a1a1-3b38eb615f01.png?resizew=351)
![](https://img.xkw.com/dksih/QBM/2021/1/26/2644603077525504/2676292530724864/STEM/a317a7f1-8485-441a-88d2-9a3047fc6a41.png?resizew=174)
如图3,测量者
使用Smart Measure测量一棵大树
的高,软件显示
,
,
,请你根据数学知识求出大树
的高.(结果可保留根号)(为了计算方便,约定
).
![](https://img.xkw.com/dksih/QBM/2021/1/26/2644603077525504/2676292530724864/STEM/50214c81-5e88-4b80-a1a1-3b38eb615f01.png?resizew=351)
![](https://img.xkw.com/dksih/QBM/2021/1/26/2644603077525504/2676292530724864/STEM/a317a7f1-8485-441a-88d2-9a3047fc6a41.png?resizew=174)
如图3,测量者
![](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/4291fc9f1f7b99e4719760c1d6cf04cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36ff5af1db74437e3614be48009bc7c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d67c49a91effde270759ba0d163b102.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df87f1b35e5b2b5e3e26d4fb221c537e.png)
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