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圆的周长动画

圆的周长动画
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2015-11-27 03:18
圆变换滑块动画
所属专题 Area, Surface Area, Volume, Cross Section, 3D Perimeter & Area Perimeter & Area Unit 11: Extending Perimeter, Circumference, and Area
这个范例演示了圆的周长计算动画。核心数学概念包括圆的周长公式和旋转变换。通过使用GeoGebra命令如Rotate、CircleArc和Dilate，可以动态展示圆的周长变化。适合初中及以上学生学习圆的基本性质和几何变换。

GeoGebra 命令及参数

  1. Center(c) → A
  2. Segment(C, B) → b
  3. Rotate(B, 114.59155902616465°, A) → B'
  4. Angle(B, A, B') → α
  5. Rotate(B', 114.59155902616465°, A) → B''
  6. Angle(B', A, B'') → β
  7. Rotate(B'', 114.59155902616465°, A) → B'''
  8. Angle(B'', A, B''') → γ
  9. Rotate(B, If[0 < d < 1, (d * α), α], A) → B'_1
  10. CircleArc(A, B, B'_1) → e
  11. Dilate(C, If[0 < d < 1, 1 - d, 0], B) → C'
  12. Segment(C', B) → f
  13. Segment(C', C) → g
  14. Rotate(e, If[1.2 ≤ d ≤ 2.2, ((d - 1.2) * α), α], A) → e'
  15. Dilate(C, If[1.2 < d < 2.2, 2.2 - d, 0], B) → C'_1
  16. Segment(C'_1, B) → h
  17. Segment(C, C'_1) → i
  18. Rotate(B, If[1.2 < d < 2.2, ((d - 1.2) * α), α], A) → B'_2
  19. CircleArc(A, B, B'_2) → k
  20. Dilate(C, If[2.4 < d < 3.4, 3.4 - d, 0], B) → C'_2
  21. Segment(C'_2, B) → j
  22. Segment(C, C'_2) → l
  23. Rotate(B, If[2.4 < d < 3.4, ((d - 2.4) * α), α], A) → B'_3
  24. CircleArc(A, B, B'_3) → p
  25. Rotate(e', If[2.4 ≤ d ≤ 3.4, ((d - 2.4) * α), α], A) → e''
  26. Rotate(k, If[2.4 ≤ d ≤ 3.4, ((d - 2.4) * α), α], A) → k'
  27. CircleArc(A, B, B') → q
  28. CircleArc(A, B''', B) → r
  29. CircleArc(A, B, B') → s
  30. CircleArc(A, B', B'') → t
  31. CircleArc(A, B'', B''') → c_1
  32. CircleArc(A, B''', B) → d_1