题目内容
函数![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/0.png)
A.(2kπ-
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/1.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/2.png)
B.(2kπ-
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/3.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/4.png)
C.(2kπ-
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/5.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/6.png)
D.(kπ-
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/7.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_ST/8.png)
【答案】分析:利用三角函数的恒等变换化简函数的解析式为 tan(
+
),令 kπ-
<
+
<kπ+
,k∈z,求得x的范围,可得函数的增区间.
解答:解:由于函数
=
=![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/8.png)
=
=
=tan(
+
),
令 kπ-
<
+
<kπ+
,k∈z,求得 x∈(2kπ-
,2k
)(k∈Z),
故函数的增区间为(2kπ-
,2k
)(k∈Z),
故选C.
点评:本题主要考查三角函数的恒等变换及化简求值,正切函数的增区间,属于中档题.
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/0.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/1.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/2.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/3.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/4.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/5.png)
解答:解:由于函数
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/6.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/7.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/8.png)
=
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/9.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/10.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/11.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/12.png)
令 kπ-
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/13.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/14.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/15.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/16.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/17.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/18.png)
故函数的增区间为(2kπ-
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/19.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131103173915346289821/SYS201311031739153462898011_DA/20.png)
故选C.
点评:本题主要考查三角函数的恒等变换及化简求值,正切函数的增区间,属于中档题.
![](http://thumb.zyjl.cn/images/loading.gif)
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