The waveform \(f(t)\) is a 10-kHz triangular wave with a peak-to-peak amplitude of \(15 \mathrm{~V}\) and a \(+7 \cdot 5-\mathrm{V}\) dc offset. Use the results in Figure 13-1 in the text to write an expression for the first four nonzero terms in the Fourier series of \(f(t)\) and plot its amplitude spectrum. Use MATLAB to plot two periods of \(f(t)\) and an estimate for \(f(t)\) using the first four nonzero terms in the Fourier series. Comment on the differences between the two waveforms.