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Soros Olympiad in Mathematics
I Soros Olympiad 1994-95 (Rus + Ukr)
10.5
product sin \frac{k'\pi}{2n} (I Soros Olympiad 1994-95 Ukraine R2 10.5)
product sin \frac{k'\pi}{2n} (I Soros Olympiad 1994-95 Ukraine R2 10.5)
Source:
June 6, 2024
trigonometry
algebra
Product
Problem Statement
For an arbitrary natural
n
n
n
, prove the equality
sin
π
2
n
sin
3
π
2
n
sin
5
π
2
n
.
.
.
sin
n
′
π
2
n
=
2
1
−
n
2
\sin \frac{\pi}{2n}\sin \frac{3\pi}{2n}\sin \frac{5\pi}{2n}...\sin \frac{n'\pi}{2n}=2^{\dfrac{1-n}{2}}
sin
2
n
π
sin
2
n
3
π
sin
2
n
5
π
...
sin
2
n
n
′
π
=
2
2
1
−
n
where
n
′
n'
n
′
is the largest odd number not exceeding
n
n
n
.
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