Hi! 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?