确定三角函数的精确值

确定三角函数的精确值
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2018-01-19 04:46
①本范例演示如何通过几何作图确定三角函数的精确值;②涉及核心数学概念包括三角函数、等边三角形、圆、角度测量;③作图要点提炼自 GeoGebra 命令:Intersect(交点)、Point(点)、Circle(圆)、Segment(线段)、Distance(距离)、Angle(角度)、Vector(向量)、Polygon(多边形)、Line(直线)、Mirror(镜像);④适合高中数学教学,用于帮助学生理解三角函数值的几何意义和计算方法。

GeoGebra 命令及参数

  1. Intersect(xAxis, yAxis) → O
  2. Point(xAxis) → E
  3. Circle(O, E) → c_1
  4. Point(c_1) → P
  5. Segment(O, P) → a
  6. Distance(P, A_1) → b
  7. Angle(E, O, P) → α
  8. Segment(A_1, (x(A_1), 0)) → f
  9. Segment(A_2, (x(A_2), 0)) → g
  10. Segment(B_2, B_1) → h
  11. Segment(C_2, C_1) → i
  12. Vector(O, P) → u
  13. Vector(P, (x(P), 0)) → v
  14. Vector(P, (0, y(P))) → w
  15. Point(u) → A
  16. Segment(A, C_2) → e
  17. Segment(A, B_2) → j
  18. Segment(A, A_2) → k
  19. Segment(A, A_3) → l
  20. Segment(A, B_3) → m
  21. Segment(A, C_3) → n
  22. Segment(A, C_4) → p
  23. Segment(A, B_4) → q
  24. Segment(A, A_4) → r
  25. Segment(A, A_1) → s_1
  26. Segment(A, B_1) → t
  27. Segment(A, C_1) → a_1
  28. Polygon(P, (x(P), 0), A) → poly1, a_2, B, b_1
  29. Polygon((abs(x(P)), abs(y(P))), A, (abs(x(P)), 0)) → poly2, d_1, e_1, a_3
  30. Point(d_1) → C
  31. Line(C, C_1) → s
  32. Point(e) → D
  33. Line(C, D) → c
  34. Point(j) → F
  35. Line(C, F) → f_1
  36. Point(k) → G
  37. Line(C, G) → g_1
  38. Point(l) → H
  39. Line(C, H) → h_1
  40. Point(m) → I
  41. Line(C, I) → i_1
  42. Intersect(c_1, c) → J, K
  43. Intersect(c_1, f_1) → L, M
  44. Intersect(c_1, h_1) → R, T
  45. Intersect(c_1, i_1) → U, V
  46. Intersect(c_1, s) → Z, D_1
  47. Segment(M, L) → l_1
  48. Segment(V, U) → m_1
  49. Segment(D_1, Z) → n_1
  50. Segment(K, J) → p_1
  51. Segment(T, R) → k_1
  52. Mirror(R, xAxis) → R'
  53. Point(l_1) → Q
  54. Line(R', Q) → j_1
  55. Intersect(c_1, j_1) → E_1, F_1
  56. Segment(F_1, E_1) → q_1