Sallows' Theorem: Triangle Medians

Sallows' Theorem: Triangle Medians
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2019-04-26 13:40
This example illustrates Sallows' Theorem, which states that the three medians of a triangle intersect at a single point, the centroid. Key concepts include triangle medians, centroid, and similar triangles. Using GeoGebra commands such as Polygon, Midpoint, and Segment, the proof of the theorem is visually demonstrated. Suitable for high school geometry students and educators.

GeoGebra Commands & Parameters

  1. Polygon(A, B, C) → t1, c, a_1, b
  2. Midpoint(b) → D
  3. Midpoint(a_1) → E
  4. Midpoint(c) → F
  5. Segment(A, E) → f
  6. Segment(B, D) → g
  7. Segment(C, F) → h
  8. Intersect(f, h) → G
  9. Polygon(A, F, G) → t2, g_1, a_2, f_1
  10. Polygon(F, B, G) → t3, g_2, f_2, b_1
  11. Polygon(A, G, D) → t4, d, a_3, g_3
  12. Polygon(G, D, C) → t5, c_1, g_4, d_1
  13. Polygon(G, B, E) → t6, e, g_5, b_2
  14. Polygon(G, E, C) → t7, c_2, g_6, e_1
  15. Vector(A, G) → u
  16. Vector(C, G) → v
  17. Vector(B, G) → w
  18. Min(1, Max[0, A1]) → A2
  19. Min(1, Max[0, A1 - 2.2]) → A4
  20. Min(1, Max[0, A1 - 1.1]) → A3
  21. Translate(A, C2) → A'
  22. Translate(G, C2) → G'
  23. Translate(D, C2) → D'
  24. Polygon(A', G', D') → t4', d', a', g'
  25. Translate(G, C2) → G'_1
  26. Translate(D, C2) → D'_1
  27. Translate(C, C2) → C'
  28. Polygon(G'_1, D'_1, C') → t5', c', g'_1, d'_1
  29. Translate(G, B2) → G'_2
  30. Translate(E, B2) → E'
  31. Translate(C, B2) → C'_1
  32. Polygon(G'_2, E', C'_1) → t7', c'_1, g'_2, e'
  33. Translate(G, B2) → G'_3
  34. Translate(B, B2) → B'
  35. Translate(E, B2) → E'_1
  36. Polygon(G'_3, B', E'_1) → t6', e'_1, g'_3, b'
  37. Translate(F, D2) → F'
  38. Translate(B, D2) → B'_1
  39. Translate(G, D2) → G'_4
  40. Polygon(F', B'_1, G'_4) → t3', g'_4, f', b'_1
  41. Translate(A, D2) → A'_1
  42. Translate(F, D2) → F'_1
  43. Translate(G, D2) → G'_5
  44. Polygon(A'_1, F'_1, G'_5) → t2', g'_5, a'_1, f'_1
  45. Rotate(A', (-((A3 * 90°))), D') → A''
  46. Rotate(G', (-((A3 * 90°))), D') → G''
  47. Rotate(D', (-((A3 * 90°))), D') → D''
  48. Polygon(A'', G'', D'') → t4'', d'', a'', g''
  49. Rotate(G'_1, (A3 * 90°), D') → H
  50. Rotate(D'_1, (A3 * 90°), D') → I
  51. Rotate(C', (A3 * 90°), D') → C''
  52. Polygon(H, I, C'') → t5'', c'', h_1, i
  53. Rotate(A'_1, (A3 * 90°), F') → J
  54. Rotate(F'_1, (A3 * 90°), F') → K
  55. Rotate(G'_5, (A3 * 90°), F') → L
  56. Polygon(J, K, L) → t2'', l, j, k
  57. Rotate(F', (-((A3 * 90°))), F') → F''
  58. Rotate(B'_1, (-((A3 * 90°))), F') → M
  59. Rotate(G'_4, (-((A3 * 90°))), F') → N
  60. Polygon(F'', M, N) → t3'', n, f'', m
  61. Rotate(G'_2, (-((A3 * 90°))), E') → O
  62. Rotate(E', (-((A3 * 90°))), E') → E''
  63. Rotate(C'_1, (-((A3 * 90°))), E') → P
  64. Polygon(O, E'', P) → t7'', p, o, e''
  65. Rotate(G'_3, (A3 * 90°), E') → Q
  66. Rotate(B', (A3 * 90°), E') → B''
  67. Rotate(E'_1, (A3 * 90°), E') → R
  68. Polygon(Q, B'', R) → t6'', r, q, b''
  69. Translate(J, D4) → J'
  70. Translate(K, D4) → K'
  71. Translate(L, D4) → L'
  72. Polygon(J', K', L') → t2''', l', j', k'
  73. Translate(F'', D4) → F'''
  74. Translate(M, D4) → M'
  75. Translate(N, D4) → N'
  76. Polygon(F''', M', N') → t3''', n', f''', m'
  77. Translate(A'', C4) → A'''
  78. Translate(G'', C4) → G'''
  79. Translate(D'', C4) → D'''
  80. Polygon(A''', G''', D''') → t4''', d''', a''', g'''
  81. Translate(H, C4) → H'
  82. Translate(I, C4) → I'
  83. Translate(C'', C4) → C'''
  84. Polygon(H', I', C''') → t5''', c''', h', i'
  85. Translate(Q, B4) → Q'
  86. Translate(B'', B4) → B'''
  87. Translate(R, B4) → R'
  88. Polygon(Q', B''', R') → t6''', r', q', b'''
  89. Translate(O, B4) → O'
  90. Translate(E'', B4) → E'''
  91. Translate(P, B4) → P'
  92. Polygon(O', E''', P') → t7''', p', o', e'''
  93. Angle(J', L', K') → α
  94. Angle(P', O', E''') → β
  95. Angle(D''', G''', A''') → δ
  96. Angle(C''', H', D''') → γ
  97. Angle(B''', Q', R') → ε
  98. Angle(F''', N', M') → ζ
  99. Angle(Q', B''', R') → η
  100. Angle(E''', P', O') → θ
  101. Angle(F''', M', N') → ι
  102. Angle(K', J', L') → κ
  103. Angle(D''', A''', G''') → λ
  104. Angle(H', C''', I') → μ

AI Drawing Prompt Reference

Draw a triangle and label its three medians, showing they intersect at a single point, the centroid. Use different colors or styles to distinguish the medians, centroid, and the triangle's interior. Construct several smaller triangles to assist in the proof. Start by drawing the original triangle, then find the midpoint of each side and connect the vertices to these midpoints to form the medians. Finally, highlight the centroid and the smaller triangles with colors or styles for clarity.
The prompt above was compiled from the original drawing commands and is for reference only.