Here is a YouTube video about Using Fourier Series to Model other Functions, and is part of a growing collection of videos I have found to be useful. The reason is how the Fourier series uses sines and cosines to model and explain others, whether even or odd functions and understanding science related to software defined radio.
This tutorial, "Using Fourier Series to Model other Functions" is free education you can watch, which will help you deepen your knowledge and be better prepared for licence exams, schoolwork, or operating radio equipment.