题目
题型:不详难度:来源:
设
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045223-53508.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045223-16817.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045223-53224.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-54892.png)
(Ⅰ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-44716.png)
(Ⅱ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-76997.png)
答案
(Ⅰ)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-44716.png)
(Ⅱ)tan(A-B)的最大值为
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-44702.png)
解析
(1)中利用正弦定理,将边化为角,得到三角函数关系式,借助于两角和差的公式得到
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-44716.png)
(2)中,分析由(I)得tanA=4tanB,故A、B都是锐角,于是tanB>0
结合两角差的正切公式以及均值不等式得到最大值。
(Ⅰ)由正弦定理得
a=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-72380.png)
acosB-bcosA=(
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045225-69191.png)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045225-60351.png)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045225-97522.png)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045225-85756.png)
依题设得
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045226-67493.png)
解得
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-44716.png)
(II)由(I)得tanA=4tanB,故A、B都是锐角,于是tanB>0
tan(A-B)=
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045226-98286.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045226-60779.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-44702.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045226-14591.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045224-44702.png)
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045211-44078.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045212-32796.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045212-45513.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045212-33954.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045212-84276.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045212-48918.png)
(1)求向量
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045212-64626.png)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045213-61550.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045212-32796.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045213-79597.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045213-29702.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045204-49943.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045204-23362.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045204-85893.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045204-13099.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045205-62055.png)
(I)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045205-83183.png)
(II)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045205-21226.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045204-13099.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045156-51040.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045156-28356.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045156-81815.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045156-11384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045156-37898.png)
(1)若
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045156-33773.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045157-89810.png)
(2)求
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045157-37664.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045150-37777.png)
A.锐角三角形 B.直角三角形
C.等腰三角形 D.等腰或直角三角形
![](http://img.shitiku.com.cn/uploads/allimg/20191020/20191020045147-16544.png)
最新试题
- 1在我国的古代四大发明向西方传播的过程中,作出贡献最大的是( )A.阿拉伯商人B.中国航海家C.意大利传教士D.波斯人
- 2关于澳门的说法,正确的是[ ]A.澳门的工业以生产重工业产品为主B.澳门的人口集中分布在岛屿上C.澳门的商业发达
- 3将过量的铁粉投入装有稀硫酸和硫酸铜的混合溶液的烧杯里,完全反应后过滤,在滤纸上留下的物质是______,在滤液里存在的物
- 4高中教材中有这样一个实验:在两支同样大小的试管中分别加入3mL(足量)稀盐酸,将两个各装有0.3g NaHCO3或Na2
- 5假如家里来了客人,我们应该[ ]①请客人坐下,并给客人沏茶②不理睬客人,只管做自己的事③有事要离开时,礼貌地向客
- 6—Why didn’t you tell him about the meeting?—He rushed out of
- 7.已知,则的解集用区间表示为
- 8标有“220V 40W”和“220V 25W”的甲、乙两盏灯串联后接到220V的电源上(设灯丝电阻不变),则下列分析正确
- 9与是定义在上的两个可导函数,若,满足,则与满足 A.B.为常数函数C.D.为常数函数
- 10你认为下列哪一事实能说明地球自转( )A.寒来暑往B.阴晴变化C.日出日落D.登高望远
热门考点
- 1某程序框图如图所示,该程序运行后输出的值是 ( )A.8B.6C.4D.3
- 2某家用电器正常工作15min消耗了0.3KW.h的电能,此电器可能是A.电水壶B.电冰箱C.电风扇 D.电视机
- 3如图所示,是用示波器显示的不同乐器发出不同声波的波形图,其中频率最大的是( )A.长笛B.小提琴C.手风琴D.二胡
- 4按要求回答问题。 一位哲人曾说过:“不仅会在欢乐时微笑,也要学会在困难时微笑。”微笑,标志着自信、雅量和大度,这是一种
- 52008年7月18日,为期两天的中国天水第三届女娲文化论坛在秦安秦融宾馆召开。女娲文化作为华夏民族的本源文化和优秀传统文
- 6东南亚人口最多的国家是[ ]A、菲律宾B、泰国C、印度尼西亚D、印度
- 7如图,已知C是AB的中点,D是AC的中点,E是BC的中点.(1)若DE=9cm,求AB的长;(2)若CE=5cm,求DB
- 8“让统治阶级在共产主义革命面前发抖吧!无产者在这个革命中失去的只是锁链。他们获得的将是整个世界。”这一名言出自A.《人权
- 9在数轴上距离原点3个单位长度的点所表示的有理数是_______
- 10 《国际歌》是全世界无产阶级的革命战歌。你知道欧仁·鲍狄埃创作《国际歌》与下列哪一历史事件有关? [