feat(Geometry/Euclidean/Angle/Unoriented/Affine): Add Theorem about Sbtw.angle_eq and Wbtw.angle_eq

[wangying11123]

add some theorems about Sbtw.angle_eq and Wbtw.angle_eq.

Main additions

_root_.Sbtw.angle_eq_right

• An Unoriented angle is unchanged by replacing the third point by one strictly further away on the same ray.

_root_.Sbtw.angle_eq_left

• An Unoriented angle is unchanged by replacing the first point by one strictly further away on the same ray.

_root_.Wbtw.angle_eq_right

• An Unoriented angle is unchanged by replacing the third point by one weakly further away on the same ray.

_root_.Wbtw.angle_eq_left

• An Unoriented angle is unchanged by replacing the first point by one weakly further away on the same ray.

[github-actions]

PR summary c05a1aed8c

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff

+ _root_.Sbtw.angle_eq_left
+ _root_.Sbtw.angle_eq_right
+ _root_.Wbtw.angle_eq_left
+ _root_.Wbtw.angle_eq_right

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

---

No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[github-actions]

✅ PR Title Formatted Correctly

The title of this PR has been updated to match our commit style conventions.
Thank you!

[jsm28]

Suggested change

	theorem _root_.Sbtw.angle_eq_right {p₁ p₂ p₃ p : P} (h : Sbtw ℝ p₂ p₃ p) :
	∠ p₁ p₂ p₃ = ∠ p₁ p₂ p := by
	rw [angle, angle]
	have h : ∃ r : ℝ, 0 < r ∧ (p₃ -ᵥ p₂) = r • (p -ᵥ p₂) := by
	have hr := sbtw_iff_mem_image_Ioo_and_ne.mp h
	obtain ⟨hr1, hr2⟩ := hr
	simp only [Set.mem_image, Set.mem_Ioo] at hr1
	obtain ⟨r, hr1, hr2⟩ := hr1
	rw [AffineMap.lineMap_apply] at hr2
	use r; repeat aesop
	obtain ⟨r, hr1,hr2⟩ := h
	rw [hr2]
	apply InnerProductGeometry.angle_smul_right_of_pos
	exact hr1
	theorem _root_.Sbtw.angle_eq_right {p₁ p₂ p₃ p : P} (h : Sbtw ℝ p₂ p₃ p) :
	∠ p₁ p₂ p₃ = ∠ p₁ p₂ p :=
	angle_eq_angle_of_angle_eq_pi _ h.angle₁₂₃_eq_pi