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cube_dihedral_theta

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formal statement (Lean)

 112theorem cube_dihedral_theta : cube_dihedral.theta = Real.pi / 2 := by

proof body

Term-mode proof.

 113  unfold DihedralAngleData.theta cube_dihedral
 114  simp only
 115  exact Real.arccos_zero
 116
 117/-! ## §3. Flat-sum conditions
 118
 119At a hinge (edge in 3D, 2-face in 4D) embedded in flat Euclidean space,
 120the dihedral angles of the simplices meeting at the hinge sum to `2π`.
 121This is the piecewise-flat analog of "no curvature at this hinge."
 122
 123We formalize this as a condition on a `List DihedralAngleData`. -/
 124
 125/-- The sum of the `theta` values over a list of dihedral data. -/

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