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Radians in Unit Circle: Reflection, Translation, Rotation

Radians in Unit Circle: Reflection, Translation, Rotation
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2017-10-18 18:24
CircleAngleTrigonometryTransformationGeometric Construction
This GeoGebra example demonstrates the geometric meaning of radian measure on the unit circle, showing how a point moves along the circumference as the central angle changes. Core mathematics concepts include the unit circle, radians, central angles, arc length, coordinate geometry, and plane transformations such as reflection, translation, and rotation. The construction employs GeoGebra commands including Line, Circle, OrthogonalLine, Intersect, Segment, Rotate, Angle, CircleArc, Vector, Translate, Mirror, Point, Polygon, and Ray, together with objects such as center, A, B, α, F, F′, Q, Q′, and R to build arcs, projections, and transformed images. It is suitable for high school trigonometry and pre-calculus courses, as well as introductory university calculus, serving as a visual tool for radian definition, unit-circle exploration, and transformation geometry.

GeoGebra Commands & Parameters

  1. Line(A, B) → a
  2. Line(C, D) → b
  3. Circle(E, 2) → c
  4. OrthogonalLine(E, a) → d
  5. Intersect(d, a) → F
  6. Segment(A, F) → e
  7. Rotate(F, (-(180 * e / 6.28))°, E) → F'
  8. Angle(F', E, F) → α
  9. CircleArc(E, F, F') → f
  10. Vector(E, F') → u
  11. Rotate(F', 3.141592653589793, E) → F''_1
  12. Vector(P, Q) → v
  13. Translate(Q, v) → Q'
  14. Vector(Q, Q') → w
  15. Translate(Q', w) → Q''
  16. Translate(Q'', w) → Q'''
  17. Translate(Q''', w) → R
  18. Translate(R, w) → R'
  19. Vector(Q', Q'') → z
  20. Vector(Q'', Q''') → m
  21. Vector(Q''', R) → n
  22. Vector(R, R') → p
  23. Vector(P, R') → q
  24. Rotate(F', 0.7853981633974483, E) → F''
  25. Angle(F', E, F'') → β
  26. Rotate(F', 0.2617993877991494, E) → F''_2
  27. Angle(F', E, F''_2) → γ
  28. Rotate(F', 0.5235987755982988, E) → F''_3
  29. Angle(F', E, F''_3) → δ
  30. Rotate(F', 1.0471975511965976, E) → F''_4
  31. Angle(F', E, F''_4) → ε
  32. Rotate(F', 1.3089969389957472, E) → F''_5
  33. Angle(F', E, F''_5) → ζ
  34. Rotate(F', 1.5707963267948966, E) → F''_6
  35. Angle(F', E, F''_6) → η
  36. Rotate(F', 1.8325957145940461, E) → F''_7
  37. Angle(F', E, F''_7) → θ
  38. Rotate(F', 2.0943951023931953, E) → F''_8
  39. Angle(F', E, F''_8) → ι
  40. Rotate(F''_8, 0.2617993877991494, E) → U
  41. Angle(F''_8, E, U) → κ
  42. Rotate(U, 0.2617993877991494, E) → U'
  43. Angle(U, E, U') → λ
  44. Rotate(U', 0.2617993877991494, E) → U''
  45. Angle(U', E, U'') → μ
  46. Rotate(U'', 0.2617993877991494, E) → U'''
  47. Angle(U'', E, U''') → ν
  48. Rotate(U''', 0.2617993877991494, E) → V
  49. Angle(U''', E, V) → ξ
  50. Rotate(V, 0.2617993877991494, E) → V'
  51. Angle(V, E, V') → ο
  52. Rotate(V', 0.2617993877991494, E) → V''
  53. Angle(V', E, V'') → ρ
  54. Rotate(V'', 0.2617993877991494, E) → V'''
  55. Angle(V'', E, V''') → σ
  56. Rotate(V''', 0.2617993877991494, E) → W
  57. Angle(V''', E, W) → τ
  58. Rotate(W, 0.2617993877991494, E) → W'
  59. Angle(W, E, W') → υ
  60. Rotate(W', 0.2617993877991494, E) → W''
  61. Angle(W', E, W'') → ϕ
  62. Rotate(W'', 0.2617993877991494, E) → W'''
  63. Angle(W'', E, W''') → χ
  64. Rotate(W''', 0.2617993877991494, E) → Z
  65. Angle(W''', E, Z) → ψ
  66. Rotate(Z, 0.2617993877991494, E) → Z'
  67. Angle(Z, E, Z') → ω
  68. Rotate(Z', 0.2617993877991494, E) → Z''
  69. Angle(Z', E, Z'') → α_1
  70. Mirror(A_1, J) → B_1
  71. Line(B_1, a) → g
  72. OrthogonalLine(T, g) → h
  73. Intersect(g, h) → C_1
  74. Segment(J, B_1) → i
  75. Segment(B_1, C_1) → j
  76. Segment(C_1, T) → k
  77. Segment(T, J) → l
  78. Point(l) → D_1
  79. OrthogonalLine(D_1, j) → r
  80. Intersect(j, r) → E_1
  81. Segment(D_1, E_1) → s
  82. OrthogonalLine(G, a) → t
  83. Intersect(t, j) → F_1
  84. Intersect(t, l) → G_1
  85. Segment(F_1, G_1) → a_1
  86. Polygon(B_1, J, T, C_1) → poly1, b_1, j_1, t_1, c_1
  87. OrthogonalLine(E, a) → d_1
  88. Point(d_1) → H_1
  89. Segment(H_1, F''_2) → e_1
  90. Segment(H_1, F''_3) → f_1
  91. Segment(H_1, F'') → g_1
  92. Segment(H_1, F''_4) → h_1
  93. Segment(H_1, F''_5) → i_1
  94. Segment(H_1, F''_6) → k_1
  95. Segment(H_1, F''_7) → l_1
  96. Segment(H_1, F''_8) → m_1
  97. Segment(H_1, U) → n_1
  98. Segment(H_1, U') → p_1
  99. Segment(H_1, U'') → q_1
  100. Point(d_1) → I_1
  101. Segment(H_1, I_1) → r_1
  102. Segment(H_1, V) → s_1
  103. Segment(H_1, V') → a_2
  104. Segment(H_1, V'') → b_2
  105. Segment(H_1, V''') → c_2
  106. Segment(H_1, W) → d_2
  107. Segment(H_1, W') → e_2
  108. Segment(H_1, W'') → f_2
  109. Segment(H_1, W''') → g_2
  110. Segment(H_1, Z) → h_2
  111. Segment(H_1, Z') → i_2
  112. Segment(H_1, Z'') → j_2
  113. Point(d_1) → J_1
  114. Ray(H_1, J_1) → k_2
  115. Point(k_2) → K_1
  116. Segment(H_1, K_1) → l_2
  117. Segment(F', H_1) → m_2
  118. Segment(H_1, U''') → n_2
  119. Ray(H_1, K_1) → p_2
  120. Intersect(e_1, f_1) → O
  121. Point(m_2) → L_1
  122. Point(k_1) → M_1
  123. Point(n_2) → N_1
  124. Point(e_2) → P_1
  125. Point(g_1) → Q_1
  126. Point(n_1) → R_1
  127. Point(b_2) → S_1
  128. Point(h_2) → T_1
  129. Point(e_1) → U_1
  130. Point(f_1) → V_1
  131. Point(h_1) → W_1
  132. Point(i_1) → Z_1
  133. Point(l_1) → A_2
  134. Point(m_1) → B_2
  135. Point(p_1) → C_2
  136. Point(q_1) → D_2
  137. Point(s_1) → E_2
  138. Point(c_2) → F_2
  139. Point(d_2) → G_2
  140. Point(f_2) → H_2
  141. Point(g_2) → I_2
  142. Point(i_2) → J_2
  143. Point(j_2) → K_2
  144. Point(a_2) → L_2