∀ {V : Type u_1} {P : Type u_2} [inst : NormedAddCommGroup V] [inst_1 : InnerProductSpace ℝ V] [inst_2 : MetricSpace P]
  [inst_3 : NormedAddTorsor V P] [hd2 : Fact (Module.finrank ℝ V = 2)] [inst_4 : Module.Oriented ℝ V (Fin 2)]
  (t : Affine.Triangle ℝ P) {i₁ i₂ i₃ : Fin 3},
  i₁ ≠ i₂ →
    i₁ ≠ i₃ →
      i₂ ≠ i₃ →
        dist (t.points i₁) (t.points i₃) / |(EuclideanGeometry.oangle (t.points i₁) (t.points i₂) (t.points i₃)).sin| /
            2 =
          Affine.Simplex.circumradius t