What Makes a Function Odd? A Dynamic Visual Definition

What Makes a Function Odd? A Dynamic Visual Definition
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2016-11-24 12:06
This interactive GeoGebra example dynamically illustrates the definition of an odd function: for every point on the graph, its reflection through the origin also lies on the graph, with opposite y-values. The core mathematical concepts include odd function symmetry, central symmetry about the origin, and the effects of geometric transformations (rotation, translation, scaling) on function graphs. The construction uses GeoGebra commands such as PointIn, FitPoly, Mirror, Rotate, Translate, Dilate, and interactive buttons/sliders to modify the function and observe when the odd-function property holds or fails. It is suitable for high school students learning function parity, as well as introductory college courses in calculus or abstract algebra, bridging geometric intuition with algebraic definitions.

GeoGebra Commands & Parameters

  1. PointIn(a) → B
  2. PointIn(b) → C
  3. PointIn(c) → D
  4. PointIn(d) → E
  5. FitPoly(list, 4) → f
  6. Mirror(g, x = 0) → g_1
  7. Point(g) → F
  8. Intersect(h, y = 0) → G
  9. Mirror(G, x = 0) → G'
  10. Mirror(F, A) → F'
  11. Dilate(H, If[0 < e ≤ 1, 1 - e, 0], G) → H'
  12. Segment(H, H') → i
  13. Dilate(G, If[1 < e ≤ 2, 2 - e, 0], F) → G'_1
  14. Segment(G, G'_1) → j
  15. Rotate(H, If[2 < e ≤ 3, ((-(e - 2)) * pi), (-pi)], H) → H'_1
  16. Rotate(H', If[2 < e ≤ 3, ((-(e - 2)) * pi), (-pi)], H) → H''
  17. Segment(H'_1, H'') → i'
  18. Dilate(G', If[3 < e ≤ 4, 4 - e, 0], F') → G''
  19. Segment(G', G'') → k
  20. Dilate(F, If[4 < e ≤ 5, 5 - e, 0], F') → F'_1
  21. Vector(F, F'_1) → u
  22. Translate(G, u) → G'_2
  23. Translate(G'_1, u) → I
  24. Mirror(g, A) → g_2
  25. Rotate(G, If[4 < e ≤ 5, ((-(e - 4)) * pi), (-pi)], G) → G'_3
  26. Rotate(G'_1, If[4 < e ≤ 5, ((-(e - 4)) * pi), (-pi)], G) → J
  27. Segment(G'_3, J) → j'
  28. Dilate(G, If[5 < e ≤ 6, 6 - e, 0], G') → G'_4
  29. Vector(G, G'_4) → v
  30. Translate(G'_3, v) → K
  31. Translate(J, v) → J'
  32. Segment(K, J') → j''
  33. RotateText(text1, pi / 2) → text3
  34. RotateText(text2, pi / 2) → text4
  35. RotateText(text5, pi / 2) → text6