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Proof of Vertical Angles Theorem

Proof of Vertical Angles Theorem
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2016-11-03 07:33
AngleTransformationGeometric Construction
In collections Angle Congruence Theorems Proving Angle Congruence Theorems
This example demonstrates the Vertical Angles Theorem, which states that vertical angles are equal. Key mathematical concepts include angle properties and rotation transformations. Using GeoGebra commands such as Point, Rotate, Angle, Line, etc., the construction shows the rotation of angles and their vertical relationship. Suitable for middle school and above students to learn geometric proofs.

GeoGebra Commands & Parameters

  1. Point(a) → B
  2. Rotate(B, α, A) → B'
  3. Angle(B, A, B') → β
  4. Line(A, B') → b
  5. Circle(A, 1) → e
  6. Intersect(b, d) → C
  7. Circle(C, 1) → f
  8. Intersect(e, a) → D, E
  9. Intersect(e, b) → F, G
  10. Intersect(f, b) → H, I
  11. Intersect(f, d) → J, K
  12. CircleSector(C, K, I) → g
  13. CircleSector(C, I, J) → h
  14. CircleSector(A, D, F) → s
  15. CircleSector(A, F, E) → t
  16. Dilate(A, If[0 < i < 1, 1 - i], C) → A'
  17. Vector(A, A') → u
  18. Translate(s, u) → s'
  19. Translate(t, u) → t'
  20. CircleArc(C, K, I) → d_1
  21. CircleArc(C, I, J) → e_1
  22. CircleArc(A, D, F) → g_1
  23. CircleArc(A, F, E) → k_1
  24. Rotate(t', ((i * 180))°, A') → t''
  25. Rotate(s', If[0 < i ≤ 1, (i * π), π], A') → s''