In pre-calculus, the unit circle is sort of like unit streets, itâ€™s the very small circle on a graph that encompasses the coordinates. It has a radius of hence the unit. The figure here shows all the measurements of the unit circle:

Do the math dance, great for algebra, calculus and pre-cal! :) love the idea, but I think my high school students will think I'm pretty strange or crazyâ€¦