题目内容
(本小题满分13分)
已知函数
的图象按向量
平移得到函数
的图象.
(1) 求实数a、b的值;
(2) 设函数
,求函数
的单调递增区间和最值.
已知函数
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345100888.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345115520.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345131682.gif)
(1) 求实数a、b的值;
(2) 设函数
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345146830.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345162363.gif)
(1)a=1,b=0(2)
,![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345193294.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345162316.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345193294.gif)
(1) 依题意按向量0平移
得
f(x)-
=
sin[2(x+
)+
] 得f(x)=-
sin(2x+
)+![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345209215.gif)
又f(x)=acos
(x+
)+b=-
sin(2x+
)+
+b
比较得a=1,b=0 ··································································· 6分
(2)
(x)=g(x)-
f(x)=
sin(2x+
)-
cos(2x+
)-
=sin(2x+
)-![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345458259.gif)
∴
(x)的单调增区间为
,值域为
13分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345209255.gif)
f(x)-
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345209215.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345209215.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345240222.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345256246.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345209215.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345287228.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345209215.gif)
又f(x)=acos
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345318129.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345334223.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345349220.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345287228.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345349220.gif)
比较得a=1,b=0 ··································································· 6分
(2)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345396209.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345396224.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345209215.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345256246.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345458259.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345256246.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345458259.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345334223.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345458259.gif)
∴
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345396209.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345162316.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823141345193294.gif)
![](http://thumb.zyjl.cn/images/loading.gif)
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