阿基米德无限求和

阿基米德无限求和
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2019-06-28 04:40
①本范例演示了阿基米德通过无限级数逼近圆面积的几何思想;②涉及核心数学概念包括级数求和、极限、连续性、上和与下和(黎曼和)、分段函数、几何变换、几何分布;③作图要点:使用 GeoGebra 的 Point, Intersect, Sequence, Polygon, Text 命令和对象,通过滑块 n 控制级数项数,动态展示逼近过程;④适合高中及以上学生及数学爱好者学习微积分和几何思想。

GeoGebra 命令及参数

  1. Point(xAxis) → A
  2. Intersect(xAxis, yAxis) → B
  3. Sequence(((2^(k) - 1) / 2^(k), (2^(k) - 1) / 2^(k)), k, 0, n_1 - 1, 1) → l1
  4. Polygon(B, A, 4) → poly1, f, g, h, i, C, D
  5. Sequence((1, y(l1(k))), k, 1, n_1, 1) → l2
  6. Sequence(((2^(k) - 1) / 2^(k), (2^(k - 1) - 1) / 2^(k - 1)), k, 1, n_1, 1) → l4
  7. Sequence(Polygon[l1(k), l4(k), 4], k, 1, n_1 - 1, 1) → l5
  8. Sequence(Polygon[l1(k), l2(k), 4], k, 1, n_1 - 1, 1) → l3
  9. Sequence(Polygon[l4(k), l2(k), 4], k, 1, n_1 - 1, 1) → l6
  10. Sequence(Polygon[l1(k) + (0, 1 / 2^(k)), l4(k) + (0, 1 / 2^(k)), 4], k, 1, n_1 - 1, 1) → l7
  11. Text(Sum[Sequence[FractionText[l5(k)] + (If[k < n_1 - 1, "+", ""]) + (If[k ≟ 8, "+...", ""]), k, 1, n_1 - 1]], (1.03, 0.2), true, true) → text2
  12. Text(Sum[Sequence[FractionText[l5(k)] + (If[k < n_1 - 1, "+", ""]) + (If[k ≟ 8, "+...", ""]), k, 1, n_1 - 1]], (1.03, 0.35), true, true) → text1
  13. Text(Sum[Sequence[FractionText[l5(k)] + (If[k < n_1 - 1, "+", ""]) + (If[k ≟ 8, "+...", ""]), k, 1, n_1 - 1]], (1.03, 0.5), true, true) → text3