Hi, This must be one of those basic questions, but..

in my text books sinuses are claimed to be defined by a real and imaginary part, i.e. two dimensions.

Now the real part is the amplitude, but the imaginary part seems to be just a delayed version of the

amplitude. the imaginary part is said to be the phase, but phase is only a difference (delay) between two signals.

please enlighten me : why must a sinus be described with two dimensions/entities/parts and not

simply with it's amplitude (over time) ? and then : what does the second dimension describe ?

Thanks!