The triangle D₂ = {v₁, v₂, w₀} of Lemma 3.6 and its polar in the plane, as in Figure 5. The vertices p₀, p₁, p₂ are where two constraints are tight; the shared coordinate ⟨y, v₂⟩ equals 1 on the side tangent at v₂ and reaches its floor m₀ at p₂. Drawing the vertex pᵢ with probability λᵢ = (1, a₁, a₂)ᵢ⁄Λ gives a mean-zero random point with E‖y‖² ≥ 4.
drag an arrowhead · unit circle in gray · dashed lines: levels of ⟨y, v₂⟩