Write the Fourier series for the three voltage waveforms in (a) of <image 1>.
['(4 / \\pi) (sin \\pit + (1 / 2) sin 3\\pit + (1 / 4) sin 5\\pit + ....).', '(4 / \\pi) (sin \\pit + (1 / 3) sin 3\\pit + (1 / 5) sin 5\\pit + ....).', '(4 / \\pi) (sin \\pit + (1 / 2) sin 2\\pit + (1 / 4) sin 4\\pit + ....).', '(4 / \\pi) (sin \\pit + (1 / 3) sin 2\\pit + (1 / 5) sin 4\\pit + ....).']