2.6.2.21 Trigonometric Fourier series

Problem: Expand function \( f(x) \) into Fourier series in \( [-\pi ; 2) \) and plot the graph of function \( y=f(x) \) : \[ f(x)=\left\{\begin{array}{cc} 2 x, & -\pi \leq x \leq 0 \\ \frac{\pi}{2}, & 0