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Differential EquationsChallengeBoundary Values & Fourier Series

Boundary Values & Fourier Series · Challenge problem

The 2π2\pi-periodic function equal to π−x2\dfrac{\pi - x}{2} on (0,2π)(0, 2\pi) has Fourier series ∑n≥1sin⁡nxn\sum_{n\ge1}\dfrac{\sin nx}{n}. Find ∑n=1∞sin⁡nn\displaystyle\sum_{n=1}^{\infty}\dfrac{\sin n}{n}.