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National and Regional Contests
Ukraine Contests
Official Ukraine Selection Cycle
Kyiv City MO
2021 Kyiv City MO
2021 Kyiv City MO Round 1
10.1
10.1
Part of
2021 Kyiv City MO Round 1
Problems
(1)
Hardest problem on Kyiv City MO 2021. Possibly ever
Source: Kyiv City MO 2021 Round 1, Problem 10.1
12/21/2023
Prove the following inequality:
sin
1
+
sin
3
+
…
+
sin
2021
>
2
sin
1011
2
3
\sin{1} + \sin{3} + \ldots + \sin{2021} > \frac{2\sin{1011}^2}{\sqrt{3}}
sin
1
+
sin
3
+
…
+
sin
2021
>
3
2
sin
1011
2
Proposed by Oleksii Masalitin
inequalities