∀ {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] {p₁ p₂ p₃ : P},
  Real.cos (EuclideanGeometry.angle p₁ p₂ p₃) = 0 ↔ EuclideanGeometry.angle p₁ p₂ p₃ = Real.pi / 2