∀ {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] (p p₁ p₂ p₃ : P) {r : ℝ},
  r ≠ 0 →
    EuclideanGeometry.angle ((AffineMap.homothety p r) p₁) ((AffineMap.homothety p r) p₂)
        ((AffineMap.homothety p r) p₃) =
      EuclideanGeometry.angle p₁ p₂ p₃