Another interesting "angle" on them is as

-dimensional vector subspaces of an

-dimensional vector space without considering the plane

. This has the same VC-dimension (

) even if the points can be chosen anywhere rather than on the hyperplane

. Since no points on a ray can be separated, this is essentially the same as them acting on, say, a unit sphere, which has dimension

. Half of this sphere is also the same as our plane

by projection along the rays.