This quick reference is about the unit circle (or UC).
Overview of the unit circle
Basically, a UC has a radius of 1, and generally a center point of (0, 0). Overall, the UC forms a great reference for working with formulas in trigonometry. In addition, angle measurement is an important part of the UC.
So, this UC allows you to measure angles in radians and in degrees. Moreover, our UC rotates counterclockwise, from 0 degrees to 360 degrees. You can almost think of it as a starting point for angles. Also, notice how you can combine all these angles to form a circle.
Example of using the unit circle
A real-life example of using the UC is, the design of Pac-Man. You can actually use the UC as a starting point for creating Pac-Man.
The above image shows you how you can use the UC to create a Pac-Man going right-to-left. Since this UC plots counterclockwise, you would start the Pac-Man at 225 degrees, and end it at 135 degrees.
Learn more about the UC
If you want to learn more about using the UC and trigonometry, then click here.