GATE Electrical 2015 Set 1 | Question: 28

Question

The signum function is given by $sgn(x)= \begin{cases}  \dfrac{x}{ \mid x \mid }; x \neq 0&  \\ 0;x=0& \end{cases}$ The Fourier series expansion of $sgn (\cos (t) )$ has

• A. Only sine terms with all harmonics.
• B. Only cosine terms with all harmonics.
• C. Only sine terms with even numbered harmonics.
• D. Only cosine terms with odd numbered harmonics.