中线重心定理(无字证明)

中线重心定理(无字证明)
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2017-06-13 04:21
①本范例演示了如何在一个三角形中构造三条中线及其重心;②涉及的核心数学概念包括中线、重心、几何作图;③作图要点——使用了Segment(线段)、Midpoint(中点)、Intersect(交点)、Polygon(多边形)等GeoGebra命令;④适合高中数学学生用于理解中线重心定理的几何性质,可作为辅助教学工具。

GeoGebra 命令及参数

  1. Segment(A, B) → a_1
  2. Segment(B, C) → b_1
  3. Midpoint(a_1) → E_1
  4. Midpoint(b_1) → F_1
  5. Segment(C, E_1) → d_1
  6. Segment(A, F_1) → e_1
  7. Intersect(d_1, e_1) → G
  8. Segment(C, G) → c
  9. Segment(G, E_1) → d
  10. Segment(A, G) → a
  11. Segment(G, F_1) → b
  12. Segment(B, G) → e
  13. Midpoint(A, C) → E
  14. Midpoint(C, B) → D
  15. Midpoint(B, A) → F
  16. Segment(A, E) → c_1
  17. Segment(E, C) → f_1
  18. Segment(C, D) → l
  19. Segment(D, B) → m
  20. Segment(B, F) → n
  21. Segment(F, A) → p
  22. Segment(G, E) → f
  23. Segment(C, F) → g
  24. Segment(A, D) → h
  25. Segment(B, E) → i
  26. Midpoint(C, G) → H
  27. Midpoint(A, G) → I
  28. Midpoint(B, G) → J
  29. Segment(C, H) → k_1
  30. Segment(H, G) → l_1
  31. Segment(G, F) → m_1
  32. Segment(A, I) → n_1
  33. Segment(I, G) → p_1
  34. Segment(G, D) → q_1
  35. Segment(B, J) → r_1
  36. Segment(J, G) → s_1
  37. Segment(G, E) → t_1
  38. Polygon(A, B, C) → poly1, c_2, a_2, b_2