3. Suppose that f(t)=\left\{\begin{array}{ll} -1 & \text { if }-\pi<t<0 \\ 1 & \text { if } 0<t \leq \pi \end{array}\right. Extend periodically and compute the Fourier series. Show all your work and/or explain your work. What are the first 3 non-zero terms of the series?

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