Calculus, visualizations, animations, AP Calculus
SolvingTrigEquations.nb develops the idea of solving trigonometric equations with special angles by looking at a sequence of problems. The student is asked to think about solutions and to do more problems along the way.
Dover, R. (2017). Solving trigonometric equations [Mathematica notebook]. Retrieved from http://digitalcommons.imsa.edu/mathematica_notebooks/9/