题目
题型:不详难度:来源:
(参考数据:sinl8°≈0.3090,cosl8°≈0.9511,tanl8°≈0.3249,
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113934-97519.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113935-91666.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113935-41736.jpg)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113935-70023.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113935-63819.png)
在Rt△DBC中,∠DBC=90°,
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113935-23188.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113935-98976.png)
∴AD=BD-AB=30.78-17.32="13.46"
DE=AE-AD=15-13.46=1.54<4米
∴花坛需要拆除.
解析
核心考点
试题【下图是一座人行天桥的示意图,天桥的高CB为10米,坡面CA的坡角为30°.为了方便行人推车过桥,市政部门决定降低坡度,使新坡面CD的坡角为18°,若新桥脚前需留】;主要考察你对解三角形等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113929-70744.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113929-67940.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113929-51887.png)
(1)证明:
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113930-93202.png)
(2)当
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113930-39565.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113930-98808.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113927-15248.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113927-35908.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113921-66062.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113921-13697.png)
(1)求证:CD∥BF;
(2)求⊙O的半径;
(3)求弦CD的长.
例 如图,在△
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113909-60287.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113909-89148.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113910-90417.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113910-72660.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113910-49890.png)
解:延长
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113910-33447.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113911-90869.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113911-23742.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113911-66318.png)
设
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113911-83486.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113912-72504.png)
∵在△
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113909-60287.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113909-89148.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113910-90417.png)
∴∠
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113912-72152.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113912-81452.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113912-38953.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113912-36128.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113913-53477.png)
(1)仿照上例,求出
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113913-43548.png)
(2)在一次课外活动中,小刘从上例得到启发,用硬纸片做了两个直角三角形,如图1、图2.图1中,∠
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113913-72603.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113913-59504.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113913-81369.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113914-55619.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113914-76894.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113914-32290.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113914-40886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113915-67752.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113915-50085.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113915-49924.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113914-40886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113915-93465.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113915-44430.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113916-54737.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113915-93465.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113916-54737.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113916-21483.png)
①在△
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113914-40886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113915-93465.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113916-94718.png)
②在△
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113914-40886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113916-94718.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113917-43886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113917-11901.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113917-67379.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191104/20191104113904-67471.png)
最新试题
- 1如图,两个集气瓶中,上瓶装的是无色的空气,下瓶装的是红棕色的二氧化氮气体(二氧化氮的密度比空气大).当抽出玻璃片后,短时
- 2下图漫画《船在垃圾山上行》说明[ ]A.我国自然资源匮乏,且开发难度大,人均占有量少 B.我国水土流失严重,森林
- 3以下说法合理的是 [ ]A.小明在10次抛图钉的试验中发现3次钉尖朝上,由此他说钉尖朝上的概率是30% B.抛掷
- 4She got the photos of her son ____ up next to her desk so th
- 5下列实验测量数据记录正确的是( )A.用pH试纸测得0.100 mol/L醋酸的pH为3.2B.用量筒测得排水法收集制
- 6小煜同学通过学习知道,乙醇汽油是一种新型车用燃料,于是他对汽油中添加乙醇的目的进行了如下研究.【猜想】猜想1:可以减少汽
- 7同学们排成一路纵队,如果每个人都只能看见自己前面的一位同学,队就排直了,这是利用了光______传播的规律.真空中的光速
- 8改错。1. Mary as well as her sisters study Chinese in China.
- 9认识物质及其变化对把握自然规律至关重要。下列与其它物质变化类型不同的一项是( )
- 10为保障绿色、环保、安全,大港油田公司投资数亿元开发了第一座“海油陆采”基地—一埕海油田,配置海上消防安全设施,淘汰油基泥
热门考点
- 1The dull film finally ,we all rushed out of the
- 2当代流行歌手周杰伦在其歌曲《爱在西元前》中唱到:“古巴比伦王朝颁布了 ,刻在黑色的玄武岩,距今已经三千七百多年
- 3将分别标有数字2,3,4,5的四张卡片洗匀后,背面朝上放在桌面上.随机地抽取一张作为十位上的数字(不放回),再抽取一张作
- 4在生命起源的化学进化过程中,不在原始海洋中形成的是( )A.有机小分子物质B.有机大分子物质C.单细胞生物D.原始生命
- 5已知斜三棱柱ABC-A1B1C1的底面是直角三角形,∠C=90°,侧棱与底面所成的角为α(0°<α<90°),点B1在底
- 6下列事实与胶体知识有关的是 ( ) ①用盐
- 7设S={1,2,3},M={1,2},N={1,3},那么(CSM)∩(CSN)等于( )A.∅B.{1,3}C.{1
- 8Did you read the book two years ago? ______. [ ]A. Yes,
- 9下列句子中加点的词活用情况不同的一项是 ( )A.得其尤绝者家焉。B.合
- 10成功需要不懈努力,现在保证我们走向成功的第一步是[ ] A.遵守规则,努力学习B.处理好同学关系,多交朋友 C.