Multivariable Calculus Explained

Scalar calculus handles quantities at points. Vector calculus handles how those quantities change direction, flow, and swirl through space. It's the language electromagnetism, fluid dynamics, and general relativity are written in — and it's built from a handful of elegant operators.

Trigonometry is more than SOH CAH TOA. This series covers the unit circle, trig identities, inverse functions, the law of sines and cosines, and where periodic functions show up across science and engineering.

Most people use statistics as a black box for publishing. This series treats it as a way of thinking — about uncertainty, evidence, and what it means to learn something true from noisy data.