A string of length L is initially stretched into a “zigzag” profile, with linear segments of string connecting the (x, f(x)) points (0, 0), (L/4, a), (3L/4,−a), (L, 0). Compute the Fourier series coefficients c_n and the time-evolution of the string y(x,t). Compute the total energy in the tension of the initially stretched string. Compute the energy in each mode and show that the total energy agrees with the energy of the stretched string.y