Only if you’re trying to get a numerical point evaluation. For example, one can use Fourier series to represent complex signals in terms of sine waves, and then reproduce the sine waves with hardware to reproduce the original signal. This is how a simple synthesizer produces different kinds of tones.
Well, sin and cos can’t be directly computed in general, so you’ll need an approximation method such as the Taylor series to use Fourier series.
Only if you’re trying to get a numerical point evaluation. For example, one can use Fourier series to represent complex signals in terms of sine waves, and then reproduce the sine waves with hardware to reproduce the original signal. This is how a simple synthesizer produces different kinds of tones.