无字证明:摆线下的面积

无字证明:摆线下的面积
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2020-01-05 16:46
该范例通过动态几何演示了摆线(旋轮线)一个拱形下方区域的面积等于其生成圆面积的三倍这一经典结论,属于“无字证明”类型。核心数学概念包括摆线的参数方程、定积分求面积、以及几何直观与代数推导的对应关系。作图要点:使用GeoGebra的CurveCartesian命令绘制摆线参数曲线,通过Point、Intersect、Polygon等构造关键点与多边形,利用Centroid、Vector、Circle、Segment、Midpoint、Mirror、Translate等工具进行面积分割与变换,配合滑块Animation实现动态展示,并辅以文本对象说明面积关系。适合高中至大学阶段的微积分、解析几何教学,也可用于数学科普演示,帮助学生直观理解积分几何意义。

GeoGebra 命令及参数

  1. CurveCartesian((R * (i - sin(i))), (R * (1 - cos(i))), i, 0, Animation) → b
  2. Point(b) → L
  3. Intersect(xAxis, yAxis) → O
  4. Polygon(D, B, O) → poly2, i, j, l
  5. Centroid(poly2) → M
  6. Vector(M, J) → v
  7. Circle(M, If[Animation < 15, ((Animation - 10) * R / 5), R]) → h
  8. Circle(C, R) → c
  9. Segment(C, A) → d
  10. Polygon(D, E, O) → poly1, o, d_1, e
  11. Segment(D, B) → a
  12. Midpoint(a) → F
  13. Midpoint(O, B) → G
  14. Midpoint(B, E) → H
  15. CurveCartesian((R * (i - sin(i))), (R * (1 - cos(i))), i, 0, If[Animation < (2 * π), Animation, 6.283185307179586]) → f
  16. Mirror(M, a) → M'
  17. Circle(M', If[Animation < 15, ((Animation - 10) * R / 5), R]) → g
  18. Vector(M', I) → u
  19. Translate(g, Vector[(If[Animation < 15, (-10 + Animation) / 5, 1] * u)]) → g'
  20. Circle(M', If[Animation < 15, ((Animation - 10) * R / 5), R]) → p
  21. Translate(h, Vector[(If[Animation < 15, (-10 + Animation) / 5, 1] * v)]) → h'
  22. Translate(p, Vector[(If[Animation < 15, (-10 + Animation) / 5, 1] * u)]) → p'
  23. Circle(M, If[Animation < 15, ((Animation - 10) * R / 5), R]) → k
  24. Translate(k, Vector[(If[Animation < 15, (-10 + Animation) / 5, 1] * v)]) → k'
  25. CurveCartesian((R * (i - sin(i))), (R * (1 - cos(i))), i, 0, If[Animation < (2 * π), Animation, 6.283185307179586]) → m
  26. Point(m) → N
  27. Vector(D, P) → w
  28. Circle(D, If[Animation < 15, ((Animation - 10) * R / 5), R]) → q
  29. Translate(q, Vector[(If[Animation < 15, (-10 + Animation) / 5, 1] * w)]) → q'
  30. Circle(D, If[Animation < 15, ((Animation - 10) * R / 5), R]) → r
  31. Translate(r, Vector[(If[Animation < 15, (-10 + Animation) / 5, 1] * w)]) → r'
  32. Point(p') → Q
  33. Segment(I, Q) → n
  34. Point(k') → S
  35. Segment(J, S) → s
  36. Point(q') → T
  37. Segment(P, T) → a_1
  38. Midpoint(n) → U
  39. Midpoint(s) → V
  40. Midpoint(a_1) → W
  41. Midpoint(d) → Z
  42. CurveCartesian((R * (i - sin(i + π))), ((-R) * (1 - cos(i + π))) + (2 * R), i, (0 * R), If[Animation < (2 * π), Animation, 6.28319]) → z
  43. CurveCartesian((R * (i - sin(i + π))), ((-R) * (1 - cos(i + π))) + (2 * R), i, (0 * R), If[Animation < (2 * π), Animation, 6.28319]) → t
  44. CurveCartesian((R * (i - sin(i + π))), ((-R) * (1 - cos(i + π))) + (2 * R), i, (0 * R), If[Animation < π, Animation, 3.141592653589793]) → b_1
  45. Translate(q, Vector[(If[Animation < 15, (-10 + Animation) / 5, 1] * w)]) → q'_1

AI 绘图提示语参考

画一个动态的几何图形,展示一个摆线(旋轮线)下的面积等于其生成圆的三倍。首先绘制摆线,然后显示生成圆和摆线下的区域。通过动态滑块,展示摆线与圆的面积关系,并用几何方法分割和变换区域,最终证明面积关系。
以上提示语为根据原始绘图命令整理而来,仅供参考。