Posted by **Margaret** on Monday, October 14, 2013 at 2:04am.

The Fourier series expansion for the periodic function,f(t) = |sin t|is defined in its fundamental interval. Taking π = 3.142, calculate the Fourier cosine series approximation of f(t), up to the 6th harmonics when t = 1.09. Give your answer to 3 decimal places. Anybody can help?