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Complex Numbers Math Physics Pre-Calculus Proofs Proving Identities Science Trigonometry

Spin One Particle Rotates Like a Vector, z-axis

In The Feynman Lectures on Physics, Volume 3 Chapter 5, Feynman poses a challenge to the reader: show that a particular combination of plus, minus and zero states of a spin one particle transforms under a rotation just like a vector does. Here I go over how to work that problem using only what was covered in the book up to that point.

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Complex Numbers Math Math Analysis Pre-Calculus Trigonometry

Sin x from Euler’s Formula

Here’s one of the things about complex numbers which is easier if you know it so well you don’t have to think about it: the formula for sin x. Nice and easy. Assumes you already know Euler’s formula, eix = cos x + i sin x.