The sine of the circle
This project lets you trace out one period of the sine curve, and shows the relationship between the sine curve (blue) and the unit circle (orange solid).
There are two modes of control, you can switch between them with "mode switch". One lets you move along the circle, and the other along the axis of the sine wave.
The length of the orange curve on the unit circle and the dashed orange curve are always the same.
The area between the x-axis and one hump of the sine curve, between 0 and π is exactly 2.
Sine is never more than 1, and never less than -1. It's the distance that a point on the unit circle (radius 1) is from the x-axis, so it can't ever be greater than 1.
Thanks to my debuggers. @-Coralreef- had the idea to use Scratch colors for the curves. Basic idea similar to some videos on YouTube, like this one: https://www.youtube.com/watch?v=o1N5xBaagr0
Mostly pen -- the graph-paper-looking grid is made by a couple functions with pen and might be useful in other projects.
If you like really cool math plotting, check out: https://www.geogebra.org/