l3lab/ntp-mathlib huggingface dataset:
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · 

Proof state:
case refine'_1.intro.intro
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
r' : ℝ
hz : x = 0
⊢ False

Next tactic:
simpa [hz] using (h' 0).1
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · 

Proof state:
case refine'_2.intro.intro
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
r' : ℝ
hz : r' • x + y = 0
⊢ False

Next tactic:
simpa [hz] using (h' r').1
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  

Proof state:
case neg
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
⊢ Real.Angle.sign (oangle o x (r • x + y)) = Real.Angle.sign (oangle o x y)

Next tactic:
have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    obtain ⟨r', -, rfl⟩ := hz
    exact h' r'
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    

Proof state:
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
⊢ ∀ z ∈ s, oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π

Next tactic:
intro z hz
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    

Proof state:
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
z : V × V
hz : z ∈ s
⊢ oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π

Next tactic:
simp_rw [Set.mem_image] at hz
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    

Proof state:
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
z : V × V
hz : ∃ x_1 ∈ Set.univ, (x, x_1 • x + y) = z
⊢ oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π

Next tactic:
obtain ⟨r', -, rfl⟩ := hz
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    obtain ⟨r', -, rfl⟩ := hz
    

Proof state:
case intro.intro
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
r' : ℝ
⊢ oangle o (x, r' • x + y).1 (x, r' • x + y).2 ≠ 0 ∧ oangle o (x, r' • x + y).1 (x, r' • x + y).2 ≠ ↑π

Next tactic:
exact h' r'
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    obtain ⟨r', -, rfl⟩ := hz
    exact h' r'
  

Proof state:
case neg
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
hs : ∀ z ∈ s, oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π
⊢ Real.Angle.sign (oangle o x (r • x + y)) = Real.Angle.sign (oangle o x y)

Next tactic:
have hx : (x, y) ∈ s := by
    convert Set.mem_image_of_mem (fun r' : ℝ => (x, r' • x + y)) (Set.mem_univ 0)
    simp
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    obtain ⟨r', -, rfl⟩ := hz
    exact h' r'
  have hx : (x, y) ∈ s := by
    

Proof state:
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
hs : ∀ z ∈ s, oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π
⊢ (x, y) ∈ s

Next tactic:
convert Set.mem_image_of_mem (fun r' : ℝ => (x, r' • x + y)) (Set.mem_univ 0)
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    obtain ⟨r', -, rfl⟩ := hz
    exact h' r'
  have hx : (x, y) ∈ s := by
    convert Set.mem_image_of_mem (fun r' : ℝ => (x, r' • x + y)) (Set.mem_univ 0)
    

Proof state:
case h.e'_4.h.e'_4
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
hs : ∀ z ∈ s, oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π
⊢ y = 0 • x + y

Next tactic:
simp
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    obtain ⟨r', -, rfl⟩ := hz
    exact h' r'
  have hx : (x, y) ∈ s := by
    convert Set.mem_image_of_mem (fun r' : ℝ => (x, r' • x + y)) (Set.mem_univ 0)
    simp
  

Proof state:
case neg
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
hs : ∀ z ∈ s, oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π
hx : (x, y) ∈ s
⊢ Real.Angle.sign (oangle o x (r • x + y)) = Real.Angle.sign (oangle o x y)

Next tactic:
have hy : (x, r • x + y) ∈ s := Set.mem_image_of_mem _ (Set.mem_univ _)
/-- Adding a multiple of the first vector passed to `oangle` to the second vector does not change
the sign of the angle. -/
@[simp]
theorem oangle_sign_smul_add_right (x y : V) (r : ℝ) :
    (o.oangle x (r • x + y)).sign = (o.oangle x y).sign := by
  by_cases h : o.oangle x y = 0 ∨ o.oangle x y = π
  · rwa [Real.Angle.sign_eq_zero_iff.2 h, Real.Angle.sign_eq_zero_iff,
      oangle_smul_add_right_eq_zero_or_eq_pi_iff]
  have h' : ∀ r' : ℝ, o.oangle x (r' • x + y) ≠ 0 ∧ o.oangle x (r' • x + y) ≠ π := by
    intro r'
    rwa [← o.oangle_smul_add_right_eq_zero_or_eq_pi_iff r', not_or] at h
  let s : Set (V × V) := (fun r' : ℝ => (x, r' • x + y)) '' Set.univ
  have hc : IsConnected s := isConnected_univ.image _ (continuous_const.prod_mk
    ((continuous_id.smul continuous_const).add continuous_const)).continuousOn
  have hf : ContinuousOn (fun z : V × V => o.oangle z.1 z.2) s := by
    refine' ContinuousAt.continuousOn fun z hz => o.continuousAt_oangle _ _
    all_goals
      simp_rw [Set.mem_image] at hz
      obtain ⟨r', -, rfl⟩ := hz
      simp only [Prod.fst, Prod.snd]
      intro hz
    · simpa [hz] using (h' 0).1
    · simpa [hz] using (h' r').1
  have hs : ∀ z : V × V, z ∈ s → o.oangle z.1 z.2 ≠ 0 ∧ o.oangle z.1 z.2 ≠ π := by
    intro z hz
    simp_rw [Set.mem_image] at hz
    obtain ⟨r', -, rfl⟩ := hz
    exact h' r'
  have hx : (x, y) ∈ s := by
    convert Set.mem_image_of_mem (fun r' : ℝ => (x, r' • x + y)) (Set.mem_univ 0)
    simp
  have hy : (x, r • x + y) ∈ s := Set.mem_image_of_mem _ (Set.mem_univ _)
  

Proof state:
case neg
V : Type u_1
V' : Type u_2
inst✝⁵ : NormedAddCommGroup V
inst✝⁴ : NormedAddCommGroup V'
inst✝³ : InnerProductSpace ℝ V
inst✝² : InnerProductSpace ℝ V'
inst✝¹ : Fact (finrank ℝ V = 2)
inst✝ : Fact (finrank ℝ V' = 2)
o : Orientation ℝ V (Fin 2)
x y : V
r : ℝ
h : ¬(oangle o x y = 0 ∨ oangle o x y = ↑π)
h' : ∀ (r' : ℝ), oangle o x (r' • x + y) ≠ 0 ∧ oangle o x (r' • x + y) ≠ ↑π
s : Set (V × V) := (fun r' => (x, r' • x + y)) '' Set.univ
hc : IsConnected s
hf : ContinuousOn (fun z => oangle o z.1 z.2) s
hs : ∀ z ∈ s, oangle o z.1 z.2 ≠ 0 ∧ oangle o z.1 z.2 ≠ ↑π
hx : (x, y) ∈ s
hy : (x, r • x + y) ∈ s
⊢ Real.Angle.sign (oangle o x (r • x + y)) = Real.Angle.sign (oangle o x y)

Next tactic:
convert Real.Angle.sign_eq_of_continuousOn hc hf hs hx hy