Theorems · Theorem · geometry

EuclideanGeometry.oangle_sign_eq_zero_iff_collinear

∀ {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 : P}, (EuclideanGeometry.oangle p₁ p₂ p₃).sign = 0 ↔ Collinear ℝ {p₁, p₂, p₃}

An oriented angle has a sign zero if and only if the three points are collinear.

Defined in

Mathlib.Geometry.Euclidean.Angle.Oriented.Affine

Cited by

0 results in Mathlib

Foundations

Depth 283 from the axioms · uses propext, Classical.choice, Quot.sound

Assumes

NormedAddCommGroupInnerProductSpaceMetricSpaceNormedAddTorsorFactModule.Oriented