Didn't have time to finish my advanced rotation article for SoME4 so I wrapped up and submitted an entry on polynomial and integer division instead: https://allthoughts.me/blog/numbers-base-x-part-1/
It expands upon basic ideas you learn in school and might be an interesting read for the maths-curious.

Updated my old article on sine and cosine computation with sections on measurement and complex numbers: https://allthoughts.me/blog/handmade-maths-cosine-and-sine/.

Along the way I develop many of the fundamental ideas behind 2D rotation with as few dependencies as I could get away with (proper treatment would be book-length). A secondary goal is to point out connections to related subjects for curious readers who want to explore more. It may not be an easy read depending on your background, but it can easily be adapted for the needs of high school students. The section on complex numbers is my answer to the question: "If you think introducing the imaginary unit as the square root of -1 is not ideal, what would be a better alternative?"

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