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Inequality with sin

Source: Mediterranean math olympiad 2018

June 5, 2018
inequalities

Problem Statement

Let a1,a2,...,ana_1, a_2, ..., a_n be more than one real numbers, such that 0aiπ20\leq a_i\leq \frac{\pi}{2}. Prove that (1ni=1n11+sinai)(1+i=1n(sinai)1n)1.\Bigg(\frac{1}{n}\sum_{i=1}^{n}\frac{1}{1+\sin a_i}\Bigg)\Bigg(1+\prod_{i=1}^{n}(\sin a_i)^{\frac{1}{n}}\Bigg)\leq1.