问题 填空题
已知f(x)=1+sin
π
2
x
,则f(1)+f(2)+f(3)+…+f(2009)=______.
答案

f(x)=1+sin

π
2
x,

则f(1)+f(2)+f(3)+…+f(2009)

=1+sin

π
2
+1+sinπ+1+sin
2
+1+sin2π+1+sin
2
+…+1+sin
2009π
2

=2009+(sin

π
2
+sinπ+sin
2
+sin2π)+(sin
2
+sin3π+sin
2
+sin4π)+…+(sin
2005π
2
+sin1003π+sin
2007π
2
+sin1004π)

+sin

2009π
2
=2009+(sin
π
2
+sinπ+sin
2
+sin2π)+(sin
π
2
+sinπ+sin
2
+sin2π)+…+(sin
π
2
+sinπ+sin
2
+sin2π)+sin
2009π
2

=2009+0+0+…+0+sin(2×502π+

π
2

=2009+1

=2010

故答案为:2010

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