Angles between vectors are defined in inner product spaces.
There is one-to-one antilinear correspondence between continuous linear functionals and vectors.
They also provide the means of defining orthogonality between vectors (zero inner product).
This distinction between vectors and pseudovectors is often ignored, but it becomes important in studying symmetry properties.
The sylvatic cycle is the fraction of the pathogen population's lifespan spent cycling between wild animals and vectors.
General vector spaces do not possess a multiplication between vectors.
Initially, the number of contacts between individuals and vectors increases as population density increases.
Because they express a relationship between vectors, tensors themselves must be independent of a particular choice of coordinate system.
Besides just preserving length, rotations also preserve the angles between vectors.
It follows that any length-preserving transformation in R preserves the dot product, and thus the angle between vectors.