Chapter1Introduction to Trigonometry
![picture showing ocean waves](imagesChap13/ocean.jpeg)
The world is full of natural occurrences that repeat themselves in predictable, periodic ways. Sound waves, radio waves, AC electrical currents, seasonal temperature changes, and ocean tides are just a few examples of periodic phenomena which can be modeled by so called trigonometric functions.
In this chapter, we introduce periodic functions and the unit circle and explore connections between them.