The Renewal Equation

Today I was tired again and not feeling mathematically creative, so I worked on exercises in the review of trigonometry rather than doing more work on the parabola problem. A few of the exercises involved graphing trigonometric functions. I’ve always found something enchanting in the graphs of sine and cosine, especially when they dance together as shown below.

I’ve also always wondered if there is a name for the leaf-like shape formed between them

(And while we’re on the subject, check out this lovely animation I found of sine and cosine graphed side by side.)

Source