圆的割线和角度

圆的割线和角度
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2014-05-09 07:02
所属专题 Circles
①本范例演示了如何在圆上通过移动点创建割线和角度;②涉及核心数学概念包括割线定理、圆周角定理、角度测量;③作图要点:使用 GeoGebra 命令 Circle(圆)、Line(线)、OrthogonalLine(垂线)、Intersect(交点)、Rotate(旋转)、CircleArc(圆弧)、Point(点)、Segment(线段)、Angle(角度)、CircleSector(扇形)、Dilate(缩放);④适合高中数学教学和几何作图练习。

GeoGebra 命令及参数

  1. Circle(A, 5) → c
  2. Line(A, a) → b
  3. OrthogonalLine(A, a) → d
  4. Intersect(c, d, 2) → B
  5. Rotate(B, 45*°, A) → B'
  6. Rotate(B, -45*°, A) → B'_1
  7. OrthogonalLine(B', a) → e
  8. OrthogonalLine(B'_1, a) → f
  9. Intersect(c, e, 1) → C
  10. Intersect(c, f, 1) → D
  11. CircleArc(A, B'_1, B') → g
  12. CircleArc(A, C, D) → h
  13. Point(g) → E
  14. Point(h) → F
  15. CircleArc(A, D, B'_1) → k
  16. Point(k) → G
  17. Point(k) → H
  18. Line(E, H) → i
  19. Line(G, F) → j
  20. Intersect(i, j) → I
  21. Segment(I, E) → l
  22. Segment(I, G) → m
  23. Segment(I, H) → n
  24. Segment(I, F) → p
  25. Angle(H, A, G) → α
  26. Angle(E, A, F) → β
  27. Rotate(E, (-α), A) → E'
  28. Angle(H, A, G) → γ
  29. Angle(E, I, F) → δ
  30. CircleArc(A, E, F) → q
  31. CircleArc(A, E', E) → r
  32. CircleArc(A, E, E') → s
  33. CircleSector(A, E, F) → t
  34. Dilate(A, 0.05, E) → A'
  35. Rotate(A', (-α), A) → A''
  36. CircleArc(A, E, E') → c_1
  37. CircleArc(A, E, A'') → d_1
  38. CircleArc(A, A', A'') → e_1
  39. Dilate(A, 0.05, F) → A'_1
  40. Rotate(A'_1, (-δ), A) → L
  41. Rotate(L, (-δ), A) → L'
  42. CircleArc(A, H, G) → f_1
  43. CircleArc(A, G, H) → g_1
  44. Circle(I, Segment[A, A'_1]) → h_1
  45. Intersect(h_1, p, 1) → M
  46. Intersect(h_1, l, 1) → N
  47. CircleArc(I, N, M) → k_1
  48. CircleArc(A, L, F) → p_1
  49. CircleArc(A, L', L) → q_1
  50. Segment(L, A) → a_1
  51. Segment(F, A) → b_1
  52. Segment(L', A) → i_1
  53. Segment(E, A) → j_1
  54. Angle(L', A, L) → ε
  55. Angle(L, A, F) → ζ
  56. Segment(A, F) → l_1