Chapter 7.8, Problem 6P

In Problems 5.1 to 5.9, define each function by the formulas given but on the interval $(-l,l).$ [That is, replace $\pm \pi$ by $\pm l$ and $\pm \pi /2$ by $\pm l/2.$ ] Expand each function in a sine-cosine Fourier series and in a complex exponential Fourier series.