Question Number 29847 by abdo imad last updated on 12/Feb/18
![θ ∈]0,π[ find he values of Σ_(n=1) ^∞ (1/n)cos(nθ) and Σ_(n=1) ^∞ (1/n)sin(nθ) .](Q29847.png)
$$\left.\theta\:\in\right]\mathrm{0},\pi\left[\:\:\:{find}\:{he}\:{values}\:{of}\:\:\sum_{{n}=\mathrm{1}} ^{\infty} \:\frac{\mathrm{1}}{{n}}{cos}\left({n}\theta\right)\:{and}\right. \\ $$$$\sum_{{n}=\mathrm{1}} ^{\infty} \:\frac{\mathrm{1}}{{n}}{sin}\left({n}\theta\right)\:. \\ $$