Dynamic Geometry Demo for Parameter r in (-3, 3)

Dynamic Geometry Demo for Parameter r in (-3, 3)
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2017-07-09 07:32
This GeoGebra example demonstrates how a geometric configuration of points, segments, and intersections changes as the parameter r varies within the open interval -3 < r < 3. The core mathematical concept is the interplay between inequality constraints and dynamic geometry, emphasizing interval representation on the number line, point loci, and symmetry. The construction uses commands such as Point, Segment, and Intersect, with objects including r, C, f, A, b, c, and numerous labeled points (A1-A22, B1, C1) plus step markers (steps, D1-D7, E1-E2), indicating a multi-step interactive model. This is suitable for middle or high school students to explore how parameter ranges affect geometric shapes, reinforcing understanding of inequalities, coordinate geometry, and logical reasoning through visual manipulation.

GeoGebra Commands & Parameters

  1. Point(yAxis) → C
  2. Point(xAxis) → A
  3. Segment(A, (x(A), f(x(A)))) → c
  4. Segment((A1, A2), (A2, A2)) → B1
  5. Segment((A2, A2), (A2, A3)) → C1
  6. Segment((A2, A3), (A3, A3)) → B2
  7. Segment((A3, A3), (A3, A4)) → C2
  8. Segment((A3, A4), (A4, A4)) → B3
  9. Segment((A4, A4), (A4, A5)) → C3
  10. Segment((A4, A5), (A5, A5)) → B4
  11. Segment((A5, A5), (A5, A6)) → C4
  12. Segment((A5, A6), (A6, A6)) → B5
  13. Segment((A6, A6), (A6, A7)) → C5
  14. Segment((A6, A7), (A7, A7)) → B6
  15. Segment((A7, A7), (A7, A8)) → C6
  16. Segment((A7, A8), (A8, A8)) → B7
  17. Segment((A8, A8), (A8, A9)) → C7
  18. Segment((A8, A9), (A9, A9)) → B8
  19. Segment((A9, A9), (A9, A10)) → C8
  20. Segment((A9, A10), (A10, A10)) → B9
  21. Segment((A10, A10), (A10, A11)) → C9
  22. Segment((A10, A11), (A11, A11)) → B10
  23. Segment((A11, A11), (A11, A12)) → C10
  24. Segment((A11, A12), (A12, A12)) → B11
  25. Segment((A12, A12), (A12, A13)) → C11
  26. Segment((A12, A13), (A13, A13)) → B12
  27. Segment((A13, A13), (A13, A14)) → C12
  28. Segment((A13, A14), (A14, A14)) → B13
  29. Segment((A14, A14), (A14, A15)) → C13
  30. Segment((A14, A15), (A15, A15)) → B14
  31. Segment((A15, A15), (A15, A16)) → C14
  32. Segment((A15, A16), (A16, A16)) → B15
  33. Segment((A16, A16), (A16, A17)) → C15
  34. Segment((A16, A17), (A17, A17)) → B16
  35. Segment((A17, A17), (A17, A18)) → C16
  36. Segment((A17, A18), (A18, A18)) → B17
  37. Segment((A18, A18), (A18, A19)) → C17
  38. Segment((A18, A19), (A19, A19)) → B18
  39. Segment((A19, A19), (A19, A20)) → C18
  40. Segment((A19, A20), (A20, A20)) → B19
  41. Segment((A20, A20), (A20, A21)) → C19
  42. Segment((A20, A21), (A21, A21)) → B20
  43. Segment((A21, A21), (A21, A22)) → C20
  44. Segment((A21, A22), (A22, A22)) → B21
  45. Segment((A22, A22), (A22, A23)) → C21
  46. Segment((A22, A23), (A23, A23)) → B22
  47. Segment((A23, A23), (A23, A24)) → C22
  48. Segment((A23, A24), (A24, A24)) → B23
  49. Segment((A24, A24), (A24, A25)) → C23
  50. Segment((A24, A25), (A25, A25)) → B24
  51. Segment((A25, A25), (A25, A26)) → C24
  52. Segment((A25, A26), (A26, A26)) → B25
  53. Segment((A26, A26), (A26, A27)) → C25
  54. Segment((A26, A27), (A27, A27)) → B26
  55. Segment((A27, A27), (A27, A28)) → C26
  56. Segment((A27, A28), (A28, A28)) → B27
  57. Segment((A28, A28), (A28, A29)) → C27
  58. Segment((A28, A29), (A29, A29)) → B28
  59. Segment((A29, A29), (A29, A30)) → C28
  60. Segment((A29, A30), (A30, A30)) → B29
  61. Segment((A30, A30), (A30, A31)) → C29
  62. Segment((A30, A31), (A31, A31)) → B30
  63. Segment((A31, A31), (A31, A32)) → C30
  64. Segment((A31, A32), (A32, A32)) → B31
  65. Segment((A32, A32), (A32, A33)) → C31
  66. Segment((A32, A33), (A33, A33)) → B32
  67. Segment((A33, A33), (A33, A34)) → C32
  68. Segment((A33, A34), (A34, A34)) → B33
  69. Segment((A34, A34), (A34, A35)) → C33
  70. Segment((A34, A35), (A35, A35)) → B34
  71. Segment((A35, A35), (A35, A36)) → C34
  72. Segment((A35, A36), (A36, A36)) → B35
  73. Segment((A36, A36), (A36, A37)) → C35
  74. Segment((A36, A37), (A37, A37)) → B36
  75. Segment((A37, A37), (A37, A38)) → C36
  76. Segment((A37, A38), (A38, A38)) → B37
  77. Segment((A38, A38), (A38, A39)) → C37
  78. Segment((A38, A39), (A39, A39)) → B38
  79. Segment((A39, A39), (A39, A40)) → C38
  80. Intersect(f, b) → B