Basically, I want a trigonometry textbook, but a lot of the texts on trigonometry use theorems in geometry as though you are already familiar with them and simply skip proofs for these theorems (such as Pythagoras theorem, some properties of triangles, properties of quadrilaterals and triangles...
If negative numbers really are about directions, why do we call them "scalars" [e.g.: multiplying a vector by -1 is considered "multiplication of a vector by a scalar"]? Also, if they are actually vectors, why call them "numbers"?