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Dihedral Angle Calculator

Online dihedral angle: enter two plane normals; the result is the plane angle or its supplement, range [0°,180°].

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cosθ=±n₁·n₂/(|n₁||n₂|)
Normal n₁
x
y
z
Normal n₂
x
y
z

📖 Tutorial | Dihedral

1. Definition
Two half-planes about an edge form a dihedral angle; the normals give the angle or its supplement, chosen with the figure.
2. Formula & Notation
n₁,n₂Normals
3. Properties & Laws
  • cosθ=±n₁·n₂/(|n₁||n₂|);
  • Range [0°,180°];
  • Angle or 180°−angle;
  • Perpendicular planes iff dot=0.
4. Steps
  1. Enter two normals;
  2. Click "Angle";
  3. Or click "Load Example".
5. Worked Examples
Example: (0,0,1),(0,1,1): cos=1/√2, 45° or 135°.
6. Common Pitfalls
Normals give angle or supplement;
Reversing a normal flips it;
Range reaches 180°.

❓ FAQ | Dihedral

Plane angle?
Two perpendiculars at the edge.
Normals?
Angle or supplement.
Range?
[0,180°].
Perpendicular?
Dot 0.
Choose?
Use the figure.
Vs skew angle?
Up to 180°.