Dynamic Excircle Relationship in Triangles

Dynamic Excircle Relationship in Triangles
Loading the math board and drawing, please wait…
2017-07-19 06:09
This example dynamically illustrates the relationships within any triangle's excircle. It involves core concepts like excircles, triangle vertices, angles, and geometric transformations. Construction uses commands such as Rotate, Ray, Point, Segment, Circle, Intersect, Angle, Min, Line, CircleSector, OrthogonalLine, Midpoint, Polygon, Dilate, CircleArc, Vector, and Translate. Suitable for high school mathematics education to understand the intrinsic connection and dynamic changes between triangles and their excircles.

GeoGebra Commands & Parameters

  1. Rotate(B, (a * π / 180), A) → B'
  2. Ray(A, B') → g
  3. Point(g) → C
  4. Segment(A, C) → j
  5. Circle(C, 4) → c
  6. Intersect(c, g, 2) → E
  7. Ray(A, B) → f
  8. Point(f) → D
  9. Segment(C, D) → h
  10. Angle(D, C, E) → γ
  11. Rotate(D, γ / 2, C) → D'
  12. Ray(C, D') → m
  13. Segment(A, D) → i
  14. Min({i, j, h}) → b
  15. Circle(D, (0.2 * b)) → d
  16. Intersect(d, f, 2) → F
  17. Ray(D, F) → k
  18. Angle(F, D, C) → β
  19. Rotate(F, β / 2, D) → F'
  20. Ray(D, F') → n
  21. Intersect(m, n) → J
  22. Line(J, h) → l_2
  23. Intersect(k, l_2) → P
  24. Ray(C, E) → l
  25. Intersect(l, l_2) → O
  26. Angle(B, A, B') → α
  27. Circle(C, (0.2 * b)) → e
  28. Circle(D, (0.15 * b)) → p
  29. Angle(F, D, F') → δ
  30. Angle(D, C, D') → ε
  31. Intersect(e, m, 1) → G
  32. Intersect(e, h, 1) → H
  33. Intersect(p, h, 1) → I
  34. CircleSector(C, H, G) → q
  35. CircleSector(D, F, F') → r
  36. OrthogonalLine(J, k) → s
  37. OrthogonalLine(J, l) → t
  38. Intersect(s, k) → K
  39. Intersect(t, l) → L
  40. Circle(J, K) → c_1
  41. Segment(L, K) → f_1
  42. Midpoint(f_1) → M
  43. OrthogonalLine(M, f_1) → g_1
  44. Intersect(c_1, g_1, 2) → N
  45. Segment(N, C) → h_1
  46. Segment(N, D) → i_1
  47. Polygon(A, D, C) → poly1, c_2, a_1, d_2
  48. Angle(J, K, D) → ζ
  49. Angle(C, L, J) → η
  50. Dilate(A, If[0 < o ≤ 1, 1 - o, 0], D) → A'
  51. Segment(A, A') → k_1
  52. Dilate(A, If[0 < o ≤ 1, 1 - o, 0], C) → A'_1
  53. Segment(A, A'_1) → l_1
  54. Dilate(C, If[1 < o ≤ 2, 2 - o, 0], J) → C'
  55. Dilate(D, If[1 < o ≤ 2, 2 - o, 0], J) → D'_1
  56. Segment(C, C') → m_1
  57. Segment(D, D'_1) → n_1
  58. Rotate(r, If[2.5 < o ≤ 3.5, ((o - 2.5) * δ), δ], D) → r'
  59. Rotate(q, If[3.5 < o ≤ 4.5, ((o - 3.5) * ε), ε], C) → q'
  60. Dilate(J, If[5 < o ≤ 6, 6 - o, 0], L) → J'
  61. Dilate(J, If[5 < o ≤ 6, 6 - o, 0], K) → J'_1
  62. Segment(J, J'_1) → p_1
  63. Segment(J, J') → q_1
  64. Angle(L, J, K) → θ
  65. Rotate(L, If[6 < o ≤ 7, ((o - 6) * θ), θ], J) → L'
  66. CircleArc(J, L, L') → e_1
  67. Rotate(K, If[7 < o ≤ 8, ((o - 7) * ((2 * π) - θ) / 2), ((2 * π) - θ) / 2], J) → K'
  68. CircleArc(J, K, K') → r_1
  69. Rotate(N, If[8 < o ≤ 9, ((o - 8) * ((2 * π) - θ) / 2), ((2 * π) - θ) / 2], J) → N'
  70. CircleArc(J, N, N') → s_1
  71. Dilate(N, If[11 < o ≤ 12, 12 - o, 0], D) → N'_1
  72. Dilate(N, If[11 < o ≤ 12, 12 - o, 0], C) → N'_2
  73. Min(c_2, d_2) → w
  74. Circle(A, (0.15 * w)) → e_2
  75. Segment(A, C) → m_2
  76. Intersect(e_2, m_2) → S,
  77. Segment(A, D) → n_2
  78. Intersect(e_2, n_2) → T,
  79. Min({h, k_1, l_1}) → b_1
  80. Intersect(d, h, 1) → U
  81. Intersect(e, h) → W,
  82. Angle(A, C, D) → λ
  83. Angle(C, D, A) → κ
  84. Rotate(A, λ / 2, C) → A'_2
  85. Angle(A, C, A'_2) → ι
  86. Ray(C, A'_2) → t_1
  87. Rotate(C, κ / 2, D) → C'_1
  88. Angle(C, D, C'_1) → μ_1
  89. Ray(D, C'_1) → f_2
  90. Intersect(d, f_2) → A_1,
  91. CircleSector(D, U, A_1) → r_2
  92. Intersect(t_1, f_2) → Z
  93. OrthogonalLine(Z, k_1) → s_2
  94. OrthogonalLine(Z, l_1) → t_2
  95. Intersect(s_2, k_1) → B_1
  96. Intersect(t_2, l_1) → C_1
  97. Intersect(k_1, t_1) → D_1
  98. Circle(A, (0.2 * b)) → q_2
  99. Angle(D, A, C) → μ
  100. Rotate(D, μ / 2, A) → D'_2
  101. Angle(D, A, D'_2) → ν
  102. Ray(A, D'_2) → a_2
  103. Intersect(q_2, a_2) → V,
  104. Intersect(q_2, k_1) → E_1,
  105. CircleSector(A, E_1, V) → p_2
  106. Dilate(D, If[1 < o ≤ 2, 2 - o, 0], Z) → D'_3
  107. Dilate(A, If[1 < o ≤ 2, 2 - o, 0], Z) → A'_3
  108. Segment(A, A'_3) → b_2
  109. Segment(D, D'_3) → f_3
  110. Rotate(r_2, If[2.5 < o ≤ 3.5, ((o - 2.5) * κ / 2), κ / 2], D) → c_3
  111. Rotate(p_2, If[3.5 < o ≤ 4.5, ((o - 3.5) * μ / 2), μ / 2], A) → d_3
  112. Dilate(Z, If[5 < o ≤ 6, 6 - o, 0], C_1) → Z'
  113. Dilate(Z, If[5 < o ≤ 6, 6 - o, 0], B_1) → Z'_1
  114. Segment(Z, Z') → g_3
  115. Segment(Z, Z'_1) → h_3
  116. Angle(Z, B_1, A) → ξ
  117. Angle(A, C_1, Z) → ο
  118. Circle(Z, Z') → e_3
  119. Rotate(C_1, If[6 < o ≤ 9, (((o - 6) * 2) * π / 3), (2 * π)], Z) → F_1
  120. Segment(C, D_1) → i_3
  121. Intersect(e, i_3) → G_1,
  122. Dilate(C, If[9.5 < o ≤ 10.5, 10.5 - o, 0], Z) → C'_2
  123. Dilate(J, If[9.5 < o ≤ 10.5, 10.5 - o, 0], Z) → J'_2
  124. Polygon(A, Z, C) → poly2, c_4, a_3, z_1
  125. Polygon(A, D, J) → poly3, j_2, a_4, d_4
  126. CircleArc(Z, Z', F_1) → k_3
  127. Dilate(C, If[11 < o ≤ 12, 12 - o, 0], J) → C'_3
  128. Vector(C, C'_3) → u_1
  129. Dilate(C, If[1 < o ≤ 2, 2 - o, 0], O) → C'_4
  130. Dilate(D, If[1 < o ≤ 2, 2 - o, 0], P) → D'_4
  131. Segment(C, C'_4) → j_1
  132. Segment(D, D'_4) → d_1
  133. Line(C, O) → g_2
  134. Line(D, P) → h_2
  135. Circle(P, 5) → k_2
  136. Circle(O, 5) → p_3
  137. Intersect(k_2, h_2) → Q, R
  138. Intersect(p_3, g_2) → H_1, I_1
  139. Ray(P, R) → i_2
  140. Ray(O, I_1) → j_3
  141. Line(O, J) → l_3
  142. Circle(O, C) → r_3
  143. Dilate(J, If[11 < o ≤ 12, 12 - o, 0], O) → J'_3
  144. Dilate(J, If[11 < o ≤ 12, 12 - o, 0], P) → J'_4
  145. Segment(J, J'_3) → s_3
  146. Segment(J, J'_4) → t_3
  147. Dilate(D, If[12 < o ≤ 13, 13 - o, 0], P) → D'_5
  148. Vector(D, D'_5) → w_1
  149. Translate(c_3, w_1) → e_4
  150. Translate(D, w_1) → D'_6
  151. Translate(D'_3, w_1) → K_1
  152. Segment(D'_6, K_1) → b_3
  153. Angle(C, D, Z) → ρ
  154. Rotate(e_4, If[13.5 < o ≤ 14.5, ((-(o - 13.5)) * ρ), (-ρ)], P) → q_3
  155. Angle(A, C, D) → σ
  156. Rotate(C, If[15 < o ≤ 16, ((o - 15) * σ), σ], O) → C'_5
  157. Rotate(C'_4, If[15 < o ≤ 16, ((o - 15) * σ), σ], O) → J_1
  158. Segment(C'_5, J_1) → m_3
  159. Rotate(D, If[16 < o ≤ 17, (((-(o - 16)) * 2) * ρ), (-2 * ρ)], P) → D'_7
  160. Rotate(D'_4, If[16 < o ≤ 17, (((-(o - 16)) * 2) * ρ), (-2 * ρ)], P) → L_1
  161. Segment(D'_7, L_1) → n_3

AI Drawing Prompt Reference

Draw a dynamic illustration of the relationship within a triangle's incircle. Start by constructing a triangle, then rotate one vertex to create a new ray. Find a point on this ray, connect it to the opposite side, and draw a circle centered at this point, intersecting the ray at two points. Draw smaller circles centered at these points, intersecting the opposite side again. Connect these points to form a dynamic geometric figure, showcasing the intrinsic connection between the incircle and the triangle's vertices.
The prompt above was compiled from the original drawing commands and is for reference only.