Geometric Transformations Animation: Composite Rotations, Translations, and Dila

Geometric Transformations Animation: Composite Rotations, Translations, and Dila
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2016-06-15 23:28
This GeoGebra example presents an animated geometric construction that demonstrates the combined effects of rotations, translations, and dilations on circles, segments, and polygons. The core mathematical concepts include congruence transformations (rotation, translation) and similarity transformations (dilation), as well as composition of transformations. The construction uses GeoGebra commands such as Segment, Point, Dilate, Vector, Line, Translate, Angle, Rotate, Circle, Intersect, and CircleSector to create multiple interrelated objects (A, B, C, D, E, F, G, H, I, etc.), with sliders or animation controls driving continuous changes. This is suitable for middle and high school geometry classes to visualize transformation properties, motion of figures, and dynamic geometric exploration.

GeoGebra Commands & Parameters

  1. Segment(A, B) → a
  2. Point(Circle[C, a]) → D
  3. Segment(C, D) → b
  4. Dilate(A, If[0 < c ≤ 1, 1 - c, 0], D) → A'
  5. Vector(A, A') → u
  6. Line(A, D) → d
  7. Vector(A, D) → v
  8. Translate(A, v) → A'_2
  9. Translate(B, v) → B'_1
  10. Segment(A'_2, B'_1) → a'_1
  11. Angle(C, D, B'_1) → α
  12. Translate(A, u) → A'_1
  13. Translate(B, u) → B'
  14. Segment(A'_1, B') → a'
  15. Rotate(A'_1, If[1 < c ≤ 2, ((-(c - 1)) * α), (-α)], A'_1) → E
  16. Rotate(B', If[1 < c ≤ 2, ((-(c - 1)) * α), (-α)], A'_1) → B''
  17. Segment(E, B'') → a''
  18. Circle(D, 1) → e
  19. Intersect(e, a'_1, 1) → F
  20. Intersect(e, b, 1) → G
  21. Intersect(e, a'_1, 1) → H
  22. Intersect(e, a'', 1) → I
  23. CircleSector(D, I, H) → f