∀ {R : Type u_1} {V : Type u_2} {P : Type u_4} [inst : Ring R] [inst_1 : LinearOrder R] [IsStrictOrderedRing R]
  [inst_3 : AddCommGroup V] [inst_4 : Module R V] [inst_5 : AddTorsor V P] [Module.IsTorsionFree R V]
  {t : Affine.Triangle R P} {i₁ i₂ i₃ : Fin 3},
  i₁ ≠ i₂ →
    ∀ {p₁ p₂ p : P},
      Sbtw R (t.points i₂) p₁ (t.points i₃) →
        Sbtw R (t.points i₁) p₂ (t.points i₃) →
          p ∈ affineSpan R {t.points i₁, p₁} → p ∈ affineSpan R {t.points i₂, p₂} → Sbtw R (t.points i₁) p p₁