There’s a group of functions built into Processing (and almost every other programming language in the world) that can help you create great images and animations. They’re drawn from the mathematical field of trigonometry, or trig, but you don’t have to care about that. What’s important is how to use them, and what they can do for you. The attached document covers all of that. I assume that you’re at (or beyond) Week 4 of the 2D Animation & Interaction class. Just click here for the PDF: Trig For Computer Graphics