My name's Davidson Noby.
I'm a 12th grade student, learning Math/Phy & Chem.
I stumbled upon your video of the harmonic addition theorem when you were solving an integral and I was astonished. It was indeed very cool, but your proof, of comparing was indeed obviously right and Mathematically rigorous, but I wasn't satisfied.
I wanted a geometrical Proof.
So I spend an entire day, and I think I've found something really cool!
Unfortunately, I can't post more than one photo.
Can I reach out to you in some other way?