The set of all vectors ⟨x,y⟩\langle x, y \rangle⟨x,y⟩ such that x2+y2=1x^2 + y^2 = 1x2+y2=1 is:
A subspace of R2\mathbb{R}^2R2
Not a subspace
A basis for R2\mathbb{R}^2R2
A linear span