题目
题型:不详难度:来源:
如图,在△
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040623-96906.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040624-44156.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040624-76582.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040624-69217.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040624-15462.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040625-61266.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040625-99648.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040625-17092.png)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040625-24481.png)
(2)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040624-69217.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040626-33494.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040626-43750.png)
解析
试题分析:(1)∵
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040626-18075.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040626-84875.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040626-10807.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040626-33494.png)
(2)方法一、由(1)得
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040627-10032.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040627-61870.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040627-17371.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040627-21549.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040627-74426.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040628-36838.png)
则高
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040626-43750.png)
方法二、如图,作
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040624-69217.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040628-88571.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040628-28578.png)
在直角△
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040628-38834.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040629-50510.png)
则不妨设
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040629-71604.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040629-17227.png)
注意到
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040629-10534.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040629-91488.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040630-20112.png)
则
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040630-60797.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040630-58052.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040630-17019.png)
点评:解决的关键是利用三角函数值来表示边和长度,进而结合三角形的性质来得到求解。属于基础题。
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040618-92355.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040618-73132.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040618-27872.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040619-98905.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040619-90376.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040619-17769.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040619-81130.png)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040619-58948.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040613-15258.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040614-49435.png)
(1)求cosB的值;
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040614-63925.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040614-81430.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040609-15856.jpg)
A.50
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040610-15563.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040610-67786.png)
C.25
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040610-15563.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040610-57712.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040602-70710.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040602-18014.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040602-85703.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040602-85573.png)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040602-44558.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040553-66368.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040553-16897.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040553-47848.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040554-49360.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040554-54784.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040554-63996.png)
(Ⅰ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040554-84932.png)
(Ⅱ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020040555-52685.png)
最新试题
- 1直接写出计算结果:(1)﹣8+4 ÷(﹣2)=( );(2)﹣32×(﹣1)5=( )
- 2有一种单细胞动物,它的质量大约只有5克的一百万分之一,则它的质量大约是( )克.(用科学记数法表示)
- 3______-6ab+9b2=(______+3b)2.
- 4如图,在Rt△ABC中,∠ACB=90°,AC=10cm,BC=15cm,点P从A出发沿AC向C点以1厘米/秒的速度匀速
- 5下列地区属于传统工业区的是 ①美国东北部工业区 ②中国京津唐地区 ③德国南部地区 ④英国中部工业区 ⑤意
- 6分解因式-=
- 7阅读下文,完成下面问题。 赵韩王普为相①,召普问曰:“自唐季以来,数十年间,帝王凡易十姓,兵革不息,其故何也?吾欲息天
- 8It takes a long time to ________ a good fame, but this name
- 9在25℃,1.01×105Pa条件下,反应2N2O5(g)==4NO2(g)+O2(g) △H=+56.7kJ/mol能
- 101995年长春出版社出版《蒸汽机打出的天下——英国工业革命》,在这本书中不可能出现的内容是( )A.通信电缆开始铺遍
热门考点
- 1导致温室效应产生的气体主要是______;温室效应的过度产生,可能带来的一种影响是______;为了缓解温室效应,可以采
- 2图7分别为A、B、C三个城市示意图。读图回答26—29题。小题1:三个城市中,最先形成的应是( )A.A城市B.B城市
- 3范蠡曾对越王说:“古之善用兵者,因天地之常,与之俱行。”《易传》说:“终日乾乾,与时偕行。”它们说明的哲学思想是A.认识
- 4发源于我国、流经我国横横断山区的澜沧江在到达中南半岛后的名称是[ ]A.湄公河 B.湄南河 C.伊洛瓦底江 D.
- 5下面叙述正确的是( )A.过平面外一点只能作一条直线与这个平面平行B.过直线外一点只能作一个平面与这条直线平行C.
- 6该图中,能正确表示等压面分布的是 ( )
- 7【题文】的值域为A.B.C.D.
- 8下列有关苯的说法,正确的是[ ]A.苯可以在催化剂的作用下和溴水发生取代反应B.苯和乙烯都很容易发生加成反应 C
- 9Many people complain that some of KFCs in China_______the pr
- 10我国现阶段的基本经济制度是 [ ]A、以公有制经济为主