直角三角形上的正方形

直角三角形上的正方形
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2017-03-27 03:19
①本范例演示在直角三角形三边外侧分别作正方形,并探讨这些正方形与原三角形的关系;②涉及的核心数学概念包括勾股定理、正弦、余弦函数、向量及解析几何;③作图要点——使用 GeoGebra 命令 Point(点)、Intersect(交点)、Polygon(多边形)、Midpoint(中点)、Length(长度)、Sequence(序列);④适合高中数学教学,用于理解勾股定理的几何证明及三角函数的应用。

GeoGebra 命令及参数

  1. Point(yAxis) → A
  2. Intersect(xAxis, yAxis) → B
  3. Point(xAxis) → C
  4. Polygon(A, B, C) → poly1, c, a, b
  5. Polygon(A, C, 4) → poly2, f, g, h, i, D, E
  6. Polygon(B, A, 4) → poly3, j, k, l, m, F, G
  7. Polygon(C, B, 4) → poly4, n, p, q, r, H, I
  8. Midpoint(F, B) → J
  9. Midpoint(B, I) → K
  10. Midpoint(C, E) → L
  11. Midpoint(A, B) → M
  12. Midpoint(B, C) → N
  13. Midpoint(C, A) → O
  14. Length(b) → LHyp
  15. Sequence(A + (t * (C - A)), t, 0, 1, 1 / LHyp) → HypB
  16. Sequence(E + (t * (D - E)), t, 0, 1, 1 / LHyp) → HypT
  17. Sequence(A + (t * (E - A)), t, 0, 1, 1 / LHyp) → HypL
  18. Sequence(C + (t * (D - C)), t, 0, 1, 1 / LHyp) → HypR
  19. Sequence(Segment[Element[HypL, k], Element[HypR, k]], k, 1, LHyp) → HypLR
  20. Sequence(Segment[Element[HypT, k], Element[HypB, k]], k, 1, LHyp) → HypTB
  21. Length(c) → LS1
  22. Length(a) → LS2
  23. Sequence(B + (t * (A - B)), t, 0, 1, 1 / LS1) → S1B
  24. Sequence(G + (t * (F - G)), t, 0, 1, 1 / LS1) → S1T
  25. Sequence(A + (t * (F - A)), t, 0, 1, 1 / LS1) → S1R
  26. Sequence(B + (t * (G - B)), t, 0, 1, 1 / LS1) → S1L
  27. Sequence(B + (t * (C - B)), t, 0, 1, 1 / LS2) → S2B
  28. Sequence(H + (t * (I - H)), t, 0, 1, 1 / LS2) → S2T
  29. Sequence(C + (t * (I - C)), t, 0, 1, 1 / LS2) → S2L
  30. Sequence(B + (t * (H - B)), t, 0, 1, 1 / LS2) → S2R
  31. Sequence(Segment[Element[S1L, k], Element[S1R, k]], k, 1, LS1) → S1LR
  32. Sequence(Segment[Element[S2L, k], Element[S2R, k]], k, 1, LHyp) → S2LR
  33. Sequence(Segment[Element[S1T, k], Element[S1B, k]], k, 1, LS1) → S1TB
  34. Sequence(Segment[Element[S2T, k], Element[S2B, k]], k, 1, LS2) → S2TB