01 Vectors, what even are they?
The fundamental, root-of-it-all building block of linear algebra is the vector, so it's worth making sure that we're all on the same page about what exactly a vector is.
07 How to organize, add and multiply matrices
By now, I'm sure that in just anything you do in your life, you need numbers. In particular, though some fields don't just need a few numbers, they need lots of them. How do you keep track of those numbers?
12.3 Dot Product Part 1
Given two nonzero vectors in two or three dimensions, their dot product is the product of the magnitudes times cosine of the angle between the two vectors.
12.4 Cross Product Part 1
Given two nonzero vectors in two or three dimensions, their cross product is a vector with magnitude equal to the product of the magnitudes of the vectors times the sine of the angle between the vectors and direction perpendicular to the vectors.