全等弦与圆心距离

全等弦与圆心距离
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2016-07-08 03:19
①本范例演示了在圆内绘制两条全等弦时,这两条弦到圆心的距离相等的现象;②涉及的核心数学概念包括圆、全等、距离、几何作图;③作图要点——使用了Circle(圆)、Point(点)、Segment(线段)、Intersect(交点)、Midpoint(中点)、Angle(角度)、CircleSector(扇形)、Dilate(缩放)、Line(直线)、Vector(向量)、Translate(平移)、Rotate(旋转)等GeoGebra命令/对象;④适合高中数学教学,用于探究圆的性质和几何变换。

GeoGebra 命令及参数

  1. Circle(A, B) → c
  2. Point(c) → C
  3. Segment(A, C) → a
  4. Point(c) → D
  5. Point(c) → E
  6. Circle(D, Chord) → e
  7. Circle(E, Chord) → f
  8. Intersect(c, e, 1) → F
  9. Intersect(c, f, 1) → G
  10. Segment(G, E) → g
  11. Segment(D, F) → h
  12. Midpoint(g) → H
  13. Midpoint(h) → I
  14. Segment(A, H) → b
  15. Segment(A, I) → d
  16. Angle(A, I, D) → α
  17. Angle(G, H, A) → β
  18. Circle(I, (0.1 * g)) → k
  19. Circle(H, (0.1 * g)) → p
  20. Intersect(k, c, 1) → J
  21. Intersect(k, c, 1) → K
  22. Intersect(c, h, 2) → L
  23. Intersect(k, c, 1) → M
  24. Intersect(k, h) → N, O
  25. Intersect(p, g) → P, Q
  26. Intersect(k, d, 1) → R
  27. Intersect(p, b, 1) → S
  28. CircleSector(I, O, R) → q
  29. CircleSector(H, P, S) → r
  30. Dilate(E, If[0 < i ≤ 1, 1 - i, 0], G) → E'
  31. Dilate(D, If[0 < i ≤ 1, 1 - i, 0], L) → D'
  32. Segment(E, E') → j
  33. Segment(D, D') → l
  34. Line(D, j) → m
  35. Point(m) → T
  36. Angle(F, D, T) → γ
  37. Dilate(G, If[1 < i ≤ 2, 2 - i, 0], D) → G'
  38. Vector(G, G') → u
  39. Translate(E, u) → E'_1
  40. Translate(E', u) → E''
  41. Segment(E'_1, E'') → j'
  42. Rotate(E'_1, If[2 < i < 3, ((-(i - 2)) * γ), (-γ)], D) → U
  43. Rotate(E'', If[2 < i < 3, ((-(i - 2)) * γ), (-γ)], D) → E'''
  44. Segment(U, E''') → j''
  45. Dilate(A, If[3 < i ≤ 4, 4 - i, 0], H) → A'
  46. Dilate(A, If[3 < i ≤ 4, 4 - i, 0], I) → A'_1
  47. Segment(A, A') → n
  48. Segment(A, A'_1) → s
  49. Rotate(r, If[4.5 < i < 5.5, ((i - 4.5) * π / 2), π / 2], H) → r'
  50. Rotate(q, If[5.5 < i < 6.5, ((i - 5.5) * π / 2), π / 2], I) → q'
  51. Angle(H, A, I) → δ
  52. Rotate(A, If[7 < i < 8, ((i - 7) * δ), δ], A) → A'_2
  53. Rotate(A', If[7 < i < 8, ((-(i - 7)) * ((2 * π) - δ)), δ - (2 * π)], A) → A''
  54. Segment(A'_2, A'') → n'