Dot Product
Reference: “Dot products and duality | Essence of linear algebra, chapter 9”, 3Blue1Brown Algebra example: $\begin{bmatrix} 1 & 2 \end{bmatrix} \cdot \begin{bmatrix} 3 \ 4 \end{bmatrix} = 1 \cdot 3 + 2 \cdot 4$ Gemoetrically:  The dot product of v and u = (length of projection of v onto u)(length of u) Order and Symmetry Order doesn’t matter. (Length of projected v) x (Length of u) = (Length of projected u) x (Length of v)...