∀ {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)]
  {p₁ p₂ p₃ p₄ p₅ p₆ : P},
  vectorSpan ℝ {p₁, p₂} = vectorSpan ℝ {p₄, p₅} →
    vectorSpan ℝ {p₃, p₂} = vectorSpan ℝ {p₆, p₅} →
      2 • EuclideanGeometry.oangle p₁ p₂ p₃ = 2 • EuclideanGeometry.oangle p₄ p₅ p₆