Every periodic function can be decomposed into a sum of sine and cosine waves (harmonics). Geometrically, this is like adding rotating vectors ("epicycles").
Complex Exponentials: $f(t) = \sum c_n e^{in\omega t}$. Each term represents a circle of radius $|c_n|$ rotating at speed $n$. Instructions: Choose a waveform. Adjust the number of terms ($N$) to see how adding more circles refines the shape.
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