Here is a YouTube video about Intro to the Fourier Series, and is part of a growing collection of videos I have found to be useful. The reason is the method for modeling any function as a combination of sine and cosine functions and understanding science related to software defined radio.
This tutorial, "Intro to the Fourier Series" 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.