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Theorems · Theorem · geometry

EuclideanGeometry.Sphere.angle_eq_pi_div_two_iff_mem_sphere_of_isDiameter

∀ {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} {s : EuclideanGeometry.Sphere P},
  s.IsDiameter p₁ p₃ → (EuclideanGeometry.angle p₁ p₂ p₃ = Real.pi / 2 ↔ p₂ ∈ s)

Thales' theorem: The angle inscribed in a semicircle is a right angle.

Defined in
Mathlib.Geometry.Euclidean.Angle.Sphere
Cited by
2 results in Mathlib
Foundations
Depth 201 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes
NormedAddCommGroupInnerProductSpaceMetricSpaceNormedAddTorsor

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