Cross is antisymmetric, so that Cross[b, a] is -Cross[a, b]. »
Cross[{x, y}] gives the perpendicular vector {-y, x}.
In general, Cross[v1, v2, ..., vn-1] is a totally antisymmetric product which takes vectors of length and yields a vector of length that is orthogonal to all of the .
Cross[v1, v2, ...] gives the dual (Hodge star) of the wedge product of the , viewed as one-forms in dimensions.