Arc Length Formula S=Rθ

Arc Length Formula S=Rθ
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2023-01-31 08:33
This example demonstrates constructing the arc length formula S=Rθ using GeoGebra. Key mathematical concepts include circles, angles, arc length, and radius relationships. Construction involves commands like Rotate, CircleArc, OrthogonalLine, and objects such as Point, Vector. Suitable for high school students learning geometry and trigonometry, or for math teaching demonstrations.

GeoGebra Commands & Parameters

  1. Rotate((r, 0), 4, (0, 0)) → D
  2. Rotate(D, If[11.5 < a ≤ 12.5, a - 11.5, 1], M) → D'
  3. Line(M, D') → g_2
  4. OrthogonalLine(D', g_2) → h_2
  5. CircleArc(M, D, D') → c_2
  6. Circle(D', r - c_2) → d_2
  7. Intersect(d_2, h_2) → J_1, K_1
  8. If(x(J_1) > x(K_1), J_1, K_1) → L_1
  9. Segment((0, 0), (r, 0)) → f
  10. Rotate((r, 0), 1, (0, 0)) → A
  11. Rotate((r, 0), 2, (0, 0)) → B
  12. Rotate((r, 0), 3, (0, 0)) → C
  13. Rotate((r, 0), 5, (0, 0)) → E
  14. Rotate((r, 0), -1, (0, 0)) → F
  15. Rotate(f, If[0 < a ≤ 1, ((-a) * pi / 2), ((-pi)) / 2], (r, 0)) → f'
  16. Rotate(G, If[1.5 < a ≤ 2.5, a - 1.5, 1], (0, 0)) → G'
  17. CircleArc((0, 0), G, G') → c
  18. Circle(G', r - c) → d
  19. Line((0, 0), G') → g
  20. OrthogonalLine(G', g) → h
  21. Intersect(d, h, 2) → H
  22. Segment(G', H) → i
  23. Dilate(G, If[3 < a ≤ 4, 4 - a, 0], A) → G'_{1}
  24. Vector(G, G'_{1}) → u
  25. Translate(f, u) → f'_{1}
  26. Line((0, 0), A) → j
  27. OrthogonalLine(A, j) → k
  28. Point(p) → I
  29. Point(k) → J
  30. Angle(J, A, I) → α
  31. Rotate(f'_{1}, If[3 < a ≤ 4, ((-(a - 3)) * α), (-α)], G'_{1}) → l
  32. Rotate(A, If[4 < a ≤ 5, a - 4, 1], (0, 0)) → A'
  33. CircleArc((0, 0), A, A') → e
  34. Circle(A', r - e) → q
  35. Line((0, 0), A') → m
  36. OrthogonalLine(A', m) → n
  37. Intersect(q, n, 2) → K
  38. Segment(A', K) → s
  39. Dilate((0, 0), If[5.5 < a ≤ 6.5, 6.5 - a, 0], B) → L
  40. Vector(M, L) → v
  41. Translate(f, v) → f'_{2}
  42. Line(M, B) → b
  43. OrthogonalLine(B, b) → f_1
  44. Point(t) → N
  45. Point(f_1) → O
  46. Angle(O, B, N) → β
  47. Rotate(f'_{2}, If[5.5 < a ≤ 6.5, ((-(a - 5.5)) * β), (-β)], L) → g_1
  48. Rotate(B, If[6.5 < a ≤ 7.5, a - 6.5, 1], (0, 0)) → B'
  49. CircleArc(M, B, B') → c_1
  50. Line(M, B') → h_1
  51. OrthogonalLine(B', h_1) → i_1
  52. Circle(B', r - c_1) → d_1
  53. Intersect(d_1, i_1, 2) → P
  54. Dilate(M, If[8 < a ≤ 9, 9 - a, 0], C) → M'
  55. Vector(M, M') → w
  56. Translate(f, w) → f'_{3}
  57. Line(M, C) → k_1
  58. OrthogonalLine(C, k_1) → l_1
  59. Point(p_1) → Q
  60. Point(l_1) → R
  61. Angle(R, C, Q) → γ
  62. Rotate(f'_{3}, If[8 < a ≤ 9, ((-(a - 8)) * γ), (-γ)], M') → m_1
  63. Rotate(C, If[9 < a ≤ 10, a - 9, 1], M) → C'
  64. CircleArc(M, C, C') → e_1
  65. Line(M, C') → n_1
  66. OrthogonalLine(C', n_1) → q_1
  67. Circle(C', r - e_1) → r_1
  68. Intersect(r_1, q_1) → S, B_1
  69. Intersect(d_1, i_1, 1) → T
  70. Dilate(M, If[10.5 < a ≤ 11.5, 11.5 - a, 0], D) → M'_{1}
  71. Vector(M, M'_{1}) → u_1
  72. Translate(f, u_1) → f'_{4}
  73. Line(M, D) → a_1
  74. OrthogonalLine(D, a_1) → b_1
  75. Point(b_1) → U
  76. Point(t_1) → V
  77. Angle(U, D, V) → δ
  78. Rotate(f'_{4}, If[10.5 < a ≤ 11.5, ((-(a - 10.5)) * δ), (-δ)], M'_{1}) → f_2
  79. Intersect(d_2, h_2, 1) → W
  80. Rotate(M, If[13 < a ≤ 14, ((a - 13) * pi / 2), pi / 2], G) → M'_{2}
  81. Segment(G, M'_{2}) → j_2
  82. If(x(P) ≤ x(T), P, T) → A_1
  83. Segment(B', A_1) → j_1
  84. If(y(B_1) < y(S), B_1, S) → C_1
  85. Segment(C', C_1) → s_1
  86. Rotate(G, If[14 < a ≤ 15, (-(a - 14)), -1], M) → G'_{2}
  87. CircleArc(M, G'_{2}, G) → e_2
  88. Line(M, G'_{2}) → k_2
  89. Circle(G'_{2}, r - e_2) → p_2
  90. OrthogonalLine(G'_{2}, k_2) → l_2
  91. Intersect(p_2, l_2) → D_1, E_1
  92. If(y(D_1) ≤ y(E_1), D_1, E_1) → F_1
  93. Segment(G'_{2}, F_1) → m_2
  94. Rotate(D, 1, M) → D'_{1}
  95. Rotate(G, 0.5) → G'_{3}
  96. Rotate(G, 1.5) → G'_{4}
  97. Rotate(G, 2.5) → G'_{5}
  98. Rotate(G, 3.5) → G'_{6}
  99. Rotate(G, 4.5) → G'_{7}
  100. Rotate(G, -0.5) → G'_{8}
  101. If(0 < a < 14, G, G'_{2}) → H_1
  102. If(0 < a ≤ 4, G', D'_{1}, 4 ≤ a ≤ 6.5, A', 6.5 < a ≤ 9, B', 9 < a ≤ 11.5, C', 11.5 < a ≤ 14, D') → I_1
  103. Segment(G_1, I_1) → n_2
  104. Angle(H_1, G_1, I_1) → θ
  105. Segment(G_1, H_1) → q_2
  106. Segment(D', Z) → i_2
  107. CircleArc(G_1, H_1, I_1) → r_2

AI Drawing Prompt Reference

Draw a circle with a marked radius. Rotate the radius from the center to the circumference at specific angles, drawing arcs and connecting the endpoints to form angles. Draw perpendicular lines to the radius at the intersection points. Connect the center to these points to create new arcs. Repeat the rotation and arc drawing process to show the relationship between arc length and radius at different angles. The final image should include multiple arcs, angle markings, and connecting lines, clearly demonstrating the geometric meaning of the arc length formula S=Rθ.
The prompt above was compiled from the original drawing commands and is for reference only.