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National and Regional Contests
Moldova Contests
Moldova National Olympiad
2002 Moldova National Olympiad
12.8
Series
Series
Source:
August 19, 2013
trigonometry
Problem Statement
∑
n
=
1
∞
3
n
.
s
i
n
3
(
π
3
n
)
=
?
\bf{\sum_{n=1}^{\infty}3^n.sin^3(\frac{\pi}{3^n})=?}
n
=
1
∑
∞
3
n
.si
n
3
(
3
n
π
)
=
?
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