Dot product and Cross product… how do I know which one to use?
dot product gives you a scalar related to projection of one vector on the other. Cross product gives you a vector at right angles to the original two, related to the area of a parallelogram of which they form two sides. So it depends on the problem. If you have an equation, you can right (or left) multiply through using either kind, but of course you have to be consistent or you’ll get nonsense.
