6. For the periodic function v(t) = Vm cos(t) for -π/2≤t≤π/2. Do the following: (a) Sketch the function v(t) as a function of t from -27 to 2T. (b) List the relevant symmetries that can and cannot be utilized. Clearly justify for each type of symmetry. (c) Find the Fourier series representation of v(t).