P For any vector U , V and W U . The dot product of two vectors is distributive with respect to the addition of vectors. Let E and U be two unity vectors. Then, E . The last formula has many applications in physics.
Cosine rule Take a vector A and B .
Here t is the angle from A to B . If we translate triangle OAB in triangle CAB, we have the cosine rule in any triangle. Unity vectors and dot product Say E and U are unity vectors, then E . Orthonormal basis Take two orthogonal unity vectors E and V . Let r any real number.