题目内容
已知函数f(x)=sin(2x+
).
(1)求函数y=f(x)的单调递减区间.
(2)画出函数y=f(x)在区间[0,π]上的图象.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915623304.png)
(1)求函数y=f(x)的单调递减区间.
(2)画出函数y=f(x)在区间[0,π]上的图象.
(1) [kπ+
,kπ+
](k∈Z) (2)见解析
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915639337.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915655382.png)
(1)由2kπ+
≤2x+
≤2kπ+
(k∈Z),
得kπ+
≤x≤kπ+
(k∈Z).
∴函数的单调递减区间是[kπ+
,kπ+
](k∈Z).
(2)∵0≤x≤π,∴
≤2x+
≤
.列表如下:
画出图象如图所示:
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240359159982238.jpg)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915670313.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915686329.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915686349.png)
得kπ+
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915639337.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915655382.png)
∴函数的单调递减区间是[kπ+
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915639337.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915655382.png)
(2)∵0≤x≤π,∴
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915686329.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915686329.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824035915811376.png)
x | 0 | ![]() | ![]() | ![]() | ![]() | π |
2x+![]() | ![]() | ![]() | π | ![]() | 2π | ![]() |
y | ![]() | 1 | 0 | -1 | 0 | ![]() |
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240359159982238.jpg)
![](http://thumb.zyjl.cn/images/loading.gif)
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