题目内容
已知![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_ST/0.png)
【答案】分析:把函数解析式中n换为n+6,变形后利用诱导公式sin(2π+α)=cosα进行化简,得到f(n+8)=f(n),即函数周期是8,把所求的式子中括号去掉后,重新结合,根据函数的周期化简,即可求出值.
解答:解:∵
,
∴f(n+8)=sin(2π+
)=sin
=f(n),
∴f(1)+f(2)+f(3)+…+f(2010)
=251×(sin
+sin
+sin
+sin
+sin
+sin
+sin
+sin
)+sin
+sin![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/12.png)
=251×(
+1+
+0-
-1-
+0)+sin
+sin![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/18.png)
=
.
故答案为:
.
点评:此题考查了三角函数的周期性及其求法,其中根据题意利用了诱导公式得出f(n+8)=f(n)是解本题的关键.
解答:解:∵
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/0.png)
∴f(n+8)=sin(2π+
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/1.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/2.png)
∴f(1)+f(2)+f(3)+…+f(2010)
=251×(sin
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/3.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/4.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/5.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/6.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/7.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/8.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/9.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/10.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/11.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/12.png)
=251×(
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/13.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/14.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/15.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/16.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/17.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/18.png)
=
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/19.png)
故答案为:
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131024190324012984770/SYS201310241903240129847012_DA/20.png)
点评:此题考查了三角函数的周期性及其求法,其中根据题意利用了诱导公式得出f(n+8)=f(n)是解本题的关键.
![](http://thumb.zyjl.cn/images/loading.gif)
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