mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.Geometry.Euclidean.Circumcenter

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝⁴ : NormedAddCommGroup V
inst✝³ : InnerProductSpace ℝ V
inst✝² : MetricSpace P
inst✝¹ : NormedAddTorsor V P
s : AffineSubspace ℝ P
inst✝ : s.direction.HasOrthogonalProjection
ps : Set P
hnps : ps.Nonempty
p : P
hps : ps ⊆ ↑s
hp : p ∉ s
this : Nonempty ↥s
cc : P
cr : ℝ
hcccru : ∀ (y : Sphere P), y.center ∈ s ∧ ps ⊆ Metric.sphere y.center y.radius → y = { center := cc, radius := cr }
hcc : cc ∈ s
hcr : ps ⊆ Metric.sphere cc cr
x : ℝ := dist cc ↑((orthogonalProjection s) p)
y : ℝ := dist p ↑((orthogonalProjection s) p)
hy0 : y ≠ 0
ycc₂ : ℝ := (x * x + y * y - cr * cr) / (2 * y)
cc₂ : P := (ycc₂ / y) • (p -ᵥ ↑((orthogonalProjection s) p)) +ᵥ cc
cr₂ : ℝ := √(cr * cr + ycc₂ * ycc₂)
⊢ ∃! cs₂, cs₂.center ∈ affineSpan ℝ (insert p ↑s) ∧ insert p ps ⊆ Metric.sphere cs₂.center cs₂.radius

Tactic:
use ⟨cc₂, cr₂⟩

Goal state after:
case h
V : Type u_1
P : Type u_2
inst✝⁴ : NormedAddCommGroup V
inst✝³ : InnerProductSpace ℝ V
inst✝² : MetricSpace P
inst✝¹ : NormedAddTorsor V P
s : AffineSubspace ℝ P
inst✝ : s.direction.HasOrthogonalProjection
ps : Set P
hnps : ps.Nonempty
p : P
hps : ps ⊆ ↑s
hp : p ∉ s
this : Nonempty ↥s
cc : P
cr : ℝ
hcccru : ∀ (y : Sphere P), y.center ∈ s ∧ ps ⊆ Metric.sphere y.center y.radius → y = { center := cc, radius := cr }
hcc : cc ∈ s
hcr : ps ⊆ Metric.sphere cc cr
x : ℝ := ⋯
y : ℝ := ⋯
hy0 : y ≠ 0
ycc₂ : ℝ := ⋯
cc₂ : P := ⋯
cr₂ : ℝ := ⋯
⊢ (fun cs₂ ↦ cs₂.center ∈ affineSpan ℝ (insert p ↑s) ∧ insert p ps ⊆ Metric.sphere cs₂.center cs₂.radius)
      { center := cc₂, radius := cr₂ } ∧
    ∀ (y : Sphere P),
      (fun cs₂ ↦ cs₂.center ∈ affineSpan ℝ (insert p ↑s) ∧ insert p ps ⊆ Metric.sphere cs₂.center cs₂.radius) y →
        y = { center := cc₂, radius := cr₂ }
Module: Mathlib.Geometry.Euclidean.Incenter

Goal state before:
pp: case neg
V : Type u_1
P : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
n : ℕ
inst✝¹ : NeZero n
s : Simplex ℝ P n
signs : Finset (Fin (n + 1))
inst✝ : Decidable (s.ExcenterExists signs)
h : ¬∑ i, s.excenterWeightsUnnorm signs i ≠ 0
⊢ ∑ i, ((∑ i, s.excenterWeightsUnnorm signs i)⁻¹ • s.excenterWeightsUnnorm signs) i =
    if ∑ i, s.excenterWeightsUnnorm signs i ≠ 0 then 1 else 0

Tactic:
simp only [ne_eq, not_not] at h

Goal state after:
case neg
V : Type u_1
P : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
n : ℕ
inst✝¹ : NeZero n
s : Simplex ℝ P n
signs : Finset (Fin (n + 1))
inst✝ : Decidable (s.ExcenterExists signs)
h : ∑ i, s.excenterWeightsUnnorm signs i = 0
⊢ ∑ i, ((∑ i, s.excenterWeightsUnnorm signs i)⁻¹ • s.excenterWeightsUnnorm signs) i =
    if ∑ i, s.excenterWeightsUnnorm signs i ≠ 0 then 1 else 0
Module: Mathlib.Geometry.Euclidean.Sphere.OrthRadius

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
hf2 : Fact (Module.finrank ℝ V = 2)
s : Sphere P
p : P
hp : dist p s.center < s.radius
hpc : p ≠ s.center
v : ↥(s.orthRadius p).direction
hv : ∀ (w : ↥(s.orthRadius p).direction), ∃ c, c • v = w
hv0 : ↑v ≠ 0
⊢ |dist p s.center| < |s.radius|

Tactic:
abs_of_nonneg dist_nonneg

Goal state after:
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
hf2 : Fact (Module.finrank ℝ V = 2)
s : Sphere P
p : P
hp : dist p s.center < s.radius
hpc : p ≠ s.center
v : ↥(s.orthRadius p).direction
hv : ∀ (w : ↥(s.orthRadius p).direction), ∃ c, c • v = w
hv0 : ↑v ≠ 0
⊢ dist p s.center < |s.radius|
Module: Mathlib.Geometry.Euclidean.Angle.Sphere

Goal state before:
pp: V : Type u_1
inst✝² : NormedAddCommGroup V
inst✝¹ : InnerProductSpace ℝ V
inst✝ : Fact (finrank ℝ V = 2)
o : Orientation ℝ V (Fin 2)
x z : V
hxzne : x ≠ z
hxz : ‖x‖ = ‖z‖
hxyne : x ≠ 0
hxy : ‖x‖ = ‖0‖
⊢ False

Tactic:
rw [norm_zero, norm_eq_zero] at hxy

Goal state after:
V : Type u_1
inst✝² : NormedAddCommGroup V
inst✝¹ : InnerProductSpace ℝ V
inst✝ : Fact (finrank ℝ V = 2)
o : Orientation ℝ V (Fin 2)
x z : V
hxzne : x ≠ z
hxz : ‖x‖ = ‖z‖
hxyne : x ≠ 0
hxy : x = 0
⊢ False
Module: Mathlib.Geometry.Euclidean.Circumcenter

Goal state before:
pp: case h.left.right.inr
V : Type u_1
P : Type u_2
inst✝⁴ : NormedAddCommGroup V
inst✝³ : InnerProductSpace ℝ V
inst✝² : MetricSpace P
inst✝¹ : NormedAddTorsor V P
s : AffineSubspace ℝ P
inst✝ : s.direction.HasOrthogonalProjection
ps : Set P
hnps : ps.Nonempty
p : P
hps : ps ⊆ ↑s
hp : p ∉ s
this : Nonempty ↥s
cc : P
cr : ℝ
hcccru : ∀ (y : Sphere P), y.center ∈ s ∧ ps ⊆ Metric.sphere y.center y.radius → y = { center := cc, radius := cr }
hcc : cc ∈ s
hcr : ps ⊆ Metric.sphere cc cr
x : ℝ := dist cc ↑((orthogonalProjection s) p)
y : ℝ := dist p ↑((orthogonalProjection s) p)
hy0 : y ≠ 0
ycc₂ : ℝ := (x * x + y * y - cr * cr) / (2 * y)
cc₂ : P := (ycc₂ / y) • (p -ᵥ ↑((orthogonalProjection s) p)) +ᵥ cc
cr₂ : ℝ := √(cr * cr + ycc₂ * ycc₂)
hpo : p = 1 • (p -ᵥ ↑((orthogonalProjection s) p)) +ᵥ ↑((orthogonalProjection s) p)
p₁ : P
hp₁ : p₁ ∈ ps
⊢ dist p₁ { center := cc₂, radius := cr₂ }.center * dist p₁ { center := cc₂, radius := cr₂ }.center =
    cr * cr + ycc₂ * ycc₂

Tactic:
· rw [dist_sq_eq_dist_orthogonalProjection_sq_add_dist_orthogonalProjection_sq _ (hps hp₁),
          orthogonalProjection_vadd_smul_vsub_orthogonalProjection _ _ hcc, Subtype.coe_mk,
          dist_of_mem_subset_mk_sphere hp₁ hcr, dist_eq_norm_vsub V cc₂ cc, vadd_vsub, norm_smul, ←
          dist_eq_norm_vsub V, Real.norm_eq_abs, abs_div, abs_of_nonneg dist_nonneg,
          div_mul_cancel₀ _ hy0, abs_mul_abs_self]

Goal state after:
Module: Mathlib.Geometry.Euclidean.Incenter

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
n : ℕ
inst✝¹ : NeZero n
s : Simplex ℝ P n
inst✝ : n.AtLeastTwo
i : Fin (n + 1)
h : (s.height i)⁻¹ + (s.height i)⁻¹ < (s.height i)⁻¹ + ∑ j ∈ {i}ᶜ, (s.height j)⁻¹
⊢ s.excenterWeights ∅ i < 2⁻¹

Tactic:
replace h : 2 * (s.height i)⁻¹ < ∑ j ∈ {i}, (s.height j)⁻¹ + ∑ j ∈ {i}ᶜ, (s.height j)⁻¹ := by
    rwa [two_mul, sum_singleton]

Goal state after:
V : Type u_1
P : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
n : ℕ
inst✝¹ : NeZero n
s : Simplex ℝ P n
inst✝ : n.AtLeastTwo
i : Fin (n + 1)
h : 2 * (s.height i)⁻¹ < ∑ j ∈ {i}, (s.height j)⁻¹ + ∑ j ∈ {i}ᶜ, (s.height j)⁻¹
⊢ s.excenterWeights ∅ i < 2⁻¹
Module: Mathlib.Geometry.Euclidean.Triangle

Goal state before:
pp: case inl
V : Type u_1
inst✝² : NormedAddCommGroup V
inst✝¹ : InnerProductSpace ℝ V
inst✝ : Fact (finrank ℝ V = 2)
o : Orientation ℝ V (Fin 2)
x y : V
h0 : o.oangle x y ≠ 0
hpi : o.oangle x y ≠ ↑π
hs : (o.oangle x (x - y)).sign = (o.oangle (y - x) y).sign
h : angle x (x - y) = angle y (y - x)
⊢ ¬o.oangle x y = ↑π

Tactic:
exact hpi

Goal state after:
Module: Mathlib.Geometry.Euclidean.Circumcenter

Goal state before:
pp: n : ℕ
i₁ i₂ : Fin (n + 1)
h : i₁ ≠ i₂
⊢ #((if i₁ ∈ univ then {i₁} else ∅) ∪ if i₂ ∈ univ then {i₂} else ∅) • 1 + #{x | ¬(x = i₁ ∨ x = i₂)} • 0 + -1 = 1

Tactic:
card_union_of_disjoint

Goal state after:
n : ℕ
i₁ i₂ : Fin (n + 1)
h : i₁ ≠ i₂
⊢ (#(if i₁ ∈ univ then {i₁} else ∅) + #(if i₂ ∈ univ then {i₂} else ∅)) • 1 + #{x | ¬(x = i₁ ∨ x = i₂)} • 0 + -1 = 1

n : ℕ
i₁ i₂ : Fin (n + 1)
h : i₁ ≠ i₂
⊢ Disjoint (if i₁ ∈ univ then {i₁} else ∅) (if i₂ ∈ univ then {i₂} else ∅)
Module: Mathlib.Geometry.Euclidean.Triangle

Goal state before:
pp: case neg
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
a b c a' b' c' : P
r : ℝ
h : ∠ a' b' c' = ∠ a b c
hab : dist a' b' = r * dist a b
hcb : dist c' b' = r * dist c b
h' : dist a' c' ^ 2 = (r * dist a c) ^ 2
hab₁ : ¬a = b
⊢ dist a' c' = r * dist a c

Tactic:
have h1 : 0 ≤ r * dist a b := by rw [← hab]; exact dist_nonneg

Goal state after:
case neg
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
a b c a' b' c' : P
r : ℝ
h : ∠ a' b' c' = ∠ a b c
hab : dist a' b' = r * dist a b
hcb : dist c' b' = r * dist c b
h' : dist a' c' ^ 2 = (r * dist a c) ^ 2
hab₁ : ¬a = b
h1 : 0 ≤ r * dist a b
⊢ dist a' c' = r * dist a c
Module: Mathlib.Geometry.Euclidean.Angle.Unoriented.TriangleInequality

Goal state before:
pp: case neg
V : Type u_1
inst✝¹ : NormedAddCommGroup V
inst✝ : InnerProductSpace ℝ V
x y : V
hx : ‖x‖ = 1
hy : ‖y‖ = 1
hxy : ¬x - ⟪x, y⟫ • y = 0
H : 1 - ⟪x, y⟫ ^ 2 ≠ 0
⊢ x = ⟪y, x⟫ • y + ((1 - ⟪y, x⟫ ^ 2) / ‖x - ⟪y, x⟫ • y‖ ^ 2) • (x - ⟪y, x⟫ • y)

Tactic:
rw [← real_inner_self_eq_norm_sq]

Goal state after:
case neg
V : Type u_1
inst✝¹ : NormedAddCommGroup V
inst✝ : InnerProductSpace ℝ V
x y : V
hx : ‖x‖ = 1
hy : ‖y‖ = 1
hxy : ¬x - ⟪x, y⟫ • y = 0
H : 1 - ⟪x, y⟫ ^ 2 ≠ 0
⊢ x = ⟪y, x⟫ • y + ((1 - ⟪y, x⟫ ^ 2) / ⟪x - ⟪y, x⟫ • y, x - ⟪y, x⟫ • y⟫) • (x - ⟪y, x⟫ • y)
Module: Mathlib.Geometry.Euclidean.Angle.Unoriented.TriangleInequality

Goal state before:
pp: case inr
V : Type u_1
inst✝¹ : NormedAddCommGroup V
inst✝ : InnerProductSpace ℝ V
x y z : V
hx : ‖x‖ = 1
hy : ‖y‖ = 1
hz : ‖z‖ = 1
H : angle x y + angle y z ≤ π
H1 :
  ⟪x, z⟫ =
    Real.cos (angle x y) * Real.cos (angle y z) +
      Real.sin (angle y z) *
        (Real.sin (angle x y) * ⟪NormedSpace.normalize (ortho y x), NormedSpace.normalize (ortho y z)⟫)
⊢ Real.cos (angle x y) * Real.cos (angle y z) - Real.sin (angle x y) * Real.sin (angle y z) ≤ ⟪x, z⟫

Tactic:
H1

Goal state after:
case inr
V : Type u_1
inst✝¹ : NormedAddCommGroup V
inst✝ : InnerProductSpace ℝ V
x y z : V
hx : ‖x‖ = 1
hy : ‖y‖ = 1
hz : ‖z‖ = 1
H : angle x y + angle y z ≤ π
H1 :
  ⟪x, z⟫ =
    Real.cos (angle x y) * Real.cos (angle y z) +
      Real.sin (angle y z) *
        (Real.sin (angle x y) * ⟪NormedSpace.normalize (ortho y x), NormedSpace.normalize (ortho y z)⟫)
⊢ Real.cos (angle x y) * Real.cos (angle y z) - Real.sin (angle x y) * Real.sin (angle y z) ≤
    Real.cos (angle x y) * Real.cos (angle y z) +
      Real.sin (angle y z) *
        (Real.sin (angle x y) * ⟪NormedSpace.normalize (ortho y x), NormedSpace.normalize (ortho y z)⟫)
Module: Mathlib.Geometry.Euclidean.Incenter

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
n : ℕ
inst✝¹ : NeZero n
s : Simplex ℝ P n
inst✝ : n.AtLeastTwo
i j : Fin (n + 1)
hne : i ≠ j
⊢ SignType.sign (s.touchpointWeights {i} i j) = 1

Tactic:
(s.excenterExists_singleton i).sign_touchpointWeights hne,

Goal state after:
V : Type u_1
P : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
n : ℕ
inst✝¹ : NeZero n
s : Simplex ℝ P n
inst✝ : n.AtLeastTwo
i j : Fin (n + 1)
hne : i ≠ j
⊢ SignType.sign (s.excenterWeights {i} j) = 1
Module: Mathlib.Geometry.Euclidean.Angle.Unoriented.TriangleInequality

Goal state before:
pp: V : Type u_1
inst✝¹ : NormedAddCommGroup V
inst✝ : InnerProductSpace ℝ V
x y z : V
hy : y ≠ 0
⊢ angle x z = angle x y + angle y z ↔ angle x z = π ∨ y ∈ Submodule.span ℝ≥0 {x, z}

Tactic:
constructor <;> rintro h

Goal state after:
case mp
V : Type u_1
inst✝¹ : NormedAddCommGroup V
inst✝ : InnerProductSpace ℝ V
x y z : V
hy : y ≠ 0
h : angle x z = angle x y + angle y z
⊢ angle x z = π ∨ y ∈ Submodule.span ℝ≥0 {x, z}

case mpr
V : Type u_1
inst✝¹ : NormedAddCommGroup V
inst✝ : InnerProductSpace ℝ V
x y z : V
hy : y ≠ 0
h : angle x z = π ∨ y ∈ Submodule.span ℝ≥0 {x, z}
⊢ angle x z = angle x y + angle y z
Module: Mathlib.Geometry.Euclidean.NinePointCircle

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P n
⊢ ((↑n + 1) / ↑n) • (s.centroid -ᵥ s.circumcenter) ∈ (affineSpan ℝ (Set.range s.points)).direction

Tactic:
apply Submodule.smul_mem

Goal state after:
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P n
⊢ s.centroid -ᵥ s.circumcenter ∈ (affineSpan ℝ (Set.range s.points)).direction
Module: Mathlib.Geometry.Euclidean.MongePoint

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
m n : ℕ
s : Simplex ℝ P n
e : Fin (n + 1) ≃ Fin (m + 1)
⊢ (s.reindex e).mongePoint = s.mongePoint

Tactic:
by
  simp_rw [mongePoint, circumcenter_reindex, centroid_def, reindex]
  obtain rfl : n = m := by simpa using Fintype.card_eq.2 ⟨e⟩
  congr 3
  convert! Finset.univ.affineCombination_map e.toEmbedding _ _ <;> simp [Function.comp_assoc]

Goal state after:
Module: Mathlib.Geometry.Euclidean.NinePointCircle

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
s : Triangle ℝ P
i : Fin 3
⊢ ↑((Simplex.faceOpposite s i).orthogonalProjectionSpan (s.points i)) =
    ↑((Simplex.faceOpposite s i).orthogonalProjectionSpan (Simplex.eulerPoint s i))

Tactic:
unfold Simplex.orthogonalProjectionSpan

Goal state after:
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
s : Triangle ℝ P
i : Fin 3
⊢ ↑((orthogonalProjection (affineSpan ℝ (Set.range (Simplex.faceOpposite s i).points))) (s.points i)) =
    ↑((orthogonalProjection (affineSpan ℝ (Set.range (Simplex.faceOpposite s i).points))) (Simplex.eulerPoint s i))
Module: Mathlib.Geometry.Euclidean.Sphere.Power

Goal state before:
pp: V : Type u_1
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
P : Type u_2
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
a b p q : P
hp : p ∈ line[ℝ, a, b]
hq : dist a q = dist b q
m : P := midpoint ℝ a b
h1 : m -ᵥ p - (m -ᵥ a) = a -ᵥ p
h1' : m -ᵥ a - (m -ᵥ p) = p -ᵥ a
h2 : m -ᵥ q - (m -ᵥ p) = p -ᵥ q
h3 : m -ᵥ q - (m -ᵥ a) = a -ᵥ q
r : P
⊢ b -ᵥ r = m -ᵥ r + ⅟2 • (b -ᵥ a)

Tactic:
← right_vsub_midpoint,

Goal state after:
V : Type u_1
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
P : Type u_2
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
a b p q : P
hp : p ∈ line[ℝ, a, b]
hq : dist a q = dist b q
m : P := midpoint ℝ a b
h1 : m -ᵥ p - (m -ᵥ a) = a -ᵥ p
h1' : m -ᵥ a - (m -ᵥ p) = p -ᵥ a
h2 : m -ᵥ q - (m -ᵥ p) = p -ᵥ q
h3 : m -ᵥ q - (m -ᵥ a) = a -ᵥ q
r : P
⊢ b -ᵥ r = m -ᵥ r + (b -ᵥ midpoint ℝ a b)
Module: Mathlib.Geometry.Euclidean.MongePoint

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
⊢ ∀ x ∈ univ,
    x ∉ fs →
      (if i₂ = i₁ ∨ True then (↑(n + 1))⁻¹ else 0) * ((if x = i₁ then 1 else 0) - if x = i₂ then 1 else 0) *
          (dist (s.points i₂) (s.points x) * dist (s.points i₂) (s.points x)) =
        0

Tactic:
intro i _ hi

Goal state after:
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
i : Fin (n + 3)
a✝ : i ∈ univ
hi : i ∉ fs
⊢ (if i₂ = i₁ ∨ True then (↑(n + 1))⁻¹ else 0) * ((if i = i₁ then 1 else 0) - if i = i₂ then 1 else 0) *
      (dist (s.points i₂) (s.points i) * dist (s.points i₂) (s.points i)) =
    0
Module: Mathlib.Geometry.Euclidean.MongePoint

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
⊢ ∀ x ∈ univ,
    x ∉ fs →
      (if True ∨ i₁ = i₂ then (↑(n + 1))⁻¹ else 0) * ((if x = i₁ then 1 else 0) - if x = i₂ then 1 else 0) *
          (dist (s.points i₁) (s.points x) * dist (s.points i₁) (s.points x)) =
        0

Tactic:
intro i _ hi

Goal state after:
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
i : Fin (n + 3)
a✝ : i ∈ univ
hi : i ∉ fs
⊢ (if True ∨ i₁ = i₂ then (↑(n + 1))⁻¹ else 0) * ((if i = i₁ then 1 else 0) - if i = i₂ then 1 else 0) *
      (dist (s.points i₁) (s.points i) * dist (s.points i₁) (s.points i)) =
    0
Module: Mathlib.Geometry.Euclidean.MongePoint

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
⊢ ∀ x ∈ univ,
    x ∉ fs →
      -2 / ↑(n + 1) * ((if x = i₁ then 1 else 0) - if x = i₂ then 1 else 0) *
          (dist s.circumcenter (s.points x) * dist s.circumcenter (s.points x)) =
        0

Tactic:
intro i _ hi

Goal state after:
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
i : Fin (n + 3)
a✝ : i ∈ univ
hi : i ∉ fs
⊢ -2 / ↑(n + 1) * ((if i = i₁ then 1 else 0) - if i = i₂ then 1 else 0) *
      (dist s.circumcenter (s.points i) * dist s.circumcenter (s.points i)) =
    0
Module: Mathlib.Geometry.Euclidean.Sphere.Power

Goal state before:
pp: V : Type u_1
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
P : Type u_2
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Oriented ℝ V (Fin 2)
p₁ p₂ p₃ p₄ p : P
h : dist p₁ p * dist p₂ p = dist p₃ p * dist p₄ p
hp₁p₂ : Sbtw ℝ p₁ p p₂
hp₃p₄ : Sbtw ℝ p₃ p p₄
hn : ¬Collinear ℝ {p₁, p, p₃}
h_angle_eq : ∠ p₁ p p₄ = ∠ p₃ p p₂
hcol_p₁pp₂ : Collinear ℝ {p₁, p, p₂}
hcol_p₃pp₄ : Collinear ℝ {p₃, p, p₄}
h_notcol_p₁p₂p₃ : ¬Collinear ℝ {p₁, p₂, p₃}
hcol : Collinear ℝ {p₁, p, p₄}
⊢ False

Tactic:
suffices hcol : Collinear ℝ ({p₁, p, p₃} : Set P) by grind

Goal state after:
V : Type u_1
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
P : Type u_2
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Oriented ℝ V (Fin 2)
p₁ p₂ p₃ p₄ p : P
h : dist p₁ p * dist p₂ p = dist p₃ p * dist p₄ p
hp₁p₂ : Sbtw ℝ p₁ p p₂
hp₃p₄ : Sbtw ℝ p₃ p p₄
hn : ¬Collinear ℝ {p₁, p, p₃}
h_angle_eq : ∠ p₁ p p₄ = ∠ p₃ p p₂
hcol_p₁pp₂ : Collinear ℝ {p₁, p, p₂}
hcol_p₃pp₄ : Collinear ℝ {p₃, p, p₄}
h_notcol_p₁p₂p₃ : ¬Collinear ℝ {p₁, p₂, p₃}
hcol : Collinear ℝ {p₁, p, p₄}
⊢ Collinear ℝ {p₁, p, p₃}
Module: Mathlib.Geometry.Euclidean.MongePoint

Goal state before:
pp: V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
⊢ ∀ x ∈ univ,
    x ∉ fs →
      ∑ i₂_1,
          (if x = i₁ ∨ x = i₂ then (↑(n + 1))⁻¹ else 0) *
              (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i₂_1 *
            (dist (s.points x) (s.pointsWithCircumcenter i₂_1) * dist (s.points x) (s.pointsWithCircumcenter i₂_1)) =
        0

Tactic:
intro i _ hi

Goal state after:
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
i₁ i₂ : Fin (n + 3)
h : ¬i₁ = i₂
hs : ∑ i, (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i = 0
fs : Finset (Fin (n + 3)) := {i₁, i₂}
hfs : ∀ i ∉ fs, i ≠ i₁ ∧ i ≠ i₂
i : Fin (n + 3)
a✝ : i ∈ univ
hi : i ∉ fs
⊢ ∑ i₂_1,
      (if i = i₁ ∨ i = i₂ then (↑(n + 1))⁻¹ else 0) *
          (pointWeightsWithCircumcenter i₁ - pointWeightsWithCircumcenter i₂) i₂_1 *
        (dist (s.points i) (s.pointsWithCircumcenter i₂_1) * dist (s.points i) (s.pointsWithCircumcenter i₂_1)) =
    0
Module: Mathlib.Geometry.Euclidean.Sphere.Power

Goal state before:
pp: V : Type u_1
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
P : Type u_2
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Oriented ℝ V (Fin 2)
p₁ p₂ p₃ p₄ p : P
h : dist p₁ p * dist p₂ p = dist p₃ p * dist p₄ p
hp₁p₂ : Sbtw ℝ p₁ p p₂
hp₃p₄ : Sbtw ℝ p₃ p p₄
hn : ¬Collinear ℝ {p₁, p, p₃}
h_angle_eq : ∠ p₁ p p₄ = ∠ p₃ p p₂
hcol_p₁pp₂ : Collinear ℝ {p₁, p, p₂}
hcol_p₃pp₄ : Collinear ℝ {p₃, p, p₄}
h_notcol_p₁p₂p₃ : ¬Collinear ℝ {p₁, p₂, p₃}
h_notcol_p₁pp₄ : ¬Collinear ℝ {p₁, p, p₄}
hcol : Collinear ℝ {p₃, p, p₂}
⊢ False

Tactic:
suffices hcol : Collinear ℝ ({p₁, p, p₃} : Set P) by grind

Goal state after:
V : Type u_1
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : InnerProductSpace ℝ V
P : Type u_2
inst✝³ : MetricSpace P
inst✝² : NormedAddTorsor V P
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Oriented ℝ V (Fin 2)
p₁ p₂ p₃ p₄ p : P
h : dist p₁ p * dist p₂ p = dist p₃ p * dist p₄ p
hp₁p₂ : Sbtw ℝ p₁ p p₂
hp₃p₄ : Sbtw ℝ p₃ p p₄
hn : ¬Collinear ℝ {p₁, p, p₃}
h_angle_eq : ∠ p₁ p p₄ = ∠ p₃ p p₂
hcol_p₁pp₂ : Collinear ℝ {p₁, p, p₂}
hcol_p₃pp₄ : Collinear ℝ {p₃, p, p₄}
h_notcol_p₁p₂p₃ : ¬Collinear ℝ {p₁, p₂, p₃}
h_notcol_p₁pp₄ : ¬Collinear ℝ {p₁, p, p₄}
hcol : Collinear ℝ {p₃, p, p₂}
⊢ Collinear ℝ {p₁, p, p₃}
Module: Mathlib.Geometry.Euclidean.MongePoint

Goal state before:
pp: case e_a.e_p
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
e : Fin (n + 3) ≃ Fin (n + 3)
i₁ i₂ : Fin (n + 3)
⊢ (affineCombination ℝ {i₁, i₂}ᶜ (s.points ∘ ⇑e.symm)) (centroidWeights ℝ {i₁, i₂}ᶜ) =
    (affineCombination ℝ {e.symm i₁, e.symm i₂}ᶜ s.points) (centroidWeights ℝ {e.symm i₁, e.symm i₂}ᶜ)

Tactic:
convert! Finset.affineCombination_map {e.symm i₁, e.symm i₂}ᶜ e.toEmbedding _ _ using 3

Goal state after:
case e'_2.e'_5.e'_9
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
e : Fin (n + 3) ≃ Fin (n + 3)
i₁ i₂ : Fin (n + 3)
⊢ {i₁, i₂}ᶜ = Finset.map e.toEmbedding {e.symm i₁, e.symm i₂}ᶜ

case e'_3.e'_5
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
e : Fin (n + 3) ≃ Fin (n + 3)
i₁ i₂ : Fin (n + 3)
⊢ s.points = (s.points ∘ ⇑e.symm) ∘ ⇑e.toEmbedding

case e'_3.e'_6
V : Type u_1
P : Type u_2
inst✝³ : NormedAddCommGroup V
inst✝² : InnerProductSpace ℝ V
inst✝¹ : MetricSpace P
inst✝ : NormedAddTorsor V P
n : ℕ
s : Simplex ℝ P (n + 2)
e : Fin (n + 3) ≃ Fin (n + 3)
i₁ i₂ : Fin (n + 3)
⊢ centroidWeights ℝ {e.symm i₁, e.symm i₂}ᶜ = centroidWeights ℝ {i₁, i₂}ᶜ ∘ ⇑e.toEmbedding