Tangram Geometry with Rotations and Constructions

Tangram Geometry with Rotations and Constructions
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2021-03-10 10:10
This example demonstrates how a tangram (seven-piece) set can be constructed and rearranged to form a target shape by explicitly building the pieces from geometric primitives. It focuses on visualizing the relationships among triangle pieces through accurate geometric construction. Key concepts include geometric construction (creating points/lines/segments and polygonal regions), right-triangle structure, and geometric transformations—especially rotation—to move pieces while maintaining their identities. Construction-wise, it uses Circle, Point, Line, Ray, and Segment to establish reference geometry; OrthogonalLine to create perpendicular constraints that support right-triangle features; Intersect to compute crucial vertices where edges meet; Polygon to assemble the tangram pieces; and Rotate to transform pieces into new positions for the拼合 (assembly) effect. The model maintains a vertex-driven workflow: many named objects correspond to original points and their rotated/derived counterparts (e.g., indexed variants like a_1, b_3, c_1, d_1, etc.). Suitable for school-level geometry learning and exploratory math activities emphasizing transformations, decomposition, and reassembly of planar figures.

GeoGebra Commands & Parameters

  1. Circle(A, a) → c
  2. Point(c) → B
  3. Line(A, B) → f
  4. OrthogonalLine(B, f) → g_{4}
  5. Circle(B, A) → d
  6. Intersect(d, g_{4}, 2) → C
  7. Polygon(A, B, C) → t1, c_1, a_1, b_{3}
  8. Circle(D, a) → e
  9. Point(e) → E
  10. Line(D, E) → h
  11. OrthogonalLine(E, h) → i
  12. Circle(E, D) → k
  13. Intersect(k, i, 2) → F
  14. Polygon(D, E, F) → t2, f_1, d_1, e_1
  15. Circle(G, a / 2) → p
  16. Point(p) → H
  17. Line(G, H) → j
  18. OrthogonalLine(H, j) → l
  19. Circle(H, G) → q
  20. Intersect(q, l, 2) → I
  21. OrthogonalLine(G, j) → m
  22. OrthogonalLine(I, m) → n
  23. Intersect(m, n) → J
  24. Polygon(G, H, I, J) → q1, g_1, h_1, i_1, j_1
  25. Circle(N, a / 2) → p_1
  26. Point(p_1) → O
  27. Line(N, O) → n_1
  28. OrthogonalLine(O, n_1) → q_1
  29. Circle(O, N) → r_1
  30. Intersect(r_1, q_1, 1) → P
  31. Polygon(O, N, P) → t4, p_2, o_1, n_2
  32. Circle(Q, (sqrt(2) / 2 * a)) → s_1
  33. Point(s_1) → R
  34. Line(Q, R) → t_1
  35. Rotate(R, ((-π)) / 4, Q) → R'
  36. Rotate(R, π / 4, Q) → R'_{1}
  37. Ray(Q, R') → b_1
  38. Circle(Q, a / 2) → d_2
  39. Intersect(d_2, b_1, 1) → S
  40. Line(S, t_1) → f_2
  41. Circle(S, (sqrt(2) / 2 * a)) → c_2
  42. Intersect(c_2, f_2, 2) → T
  43. Polygon(Q, S, T, R) → q2, q_2, s_2, t_2, r_2
  44. Ray(Q, R'_{1}) → g_2
  45. Intersect(d_2, g_2, 1) → U
  46. Line(U, t_1) → h_2
  47. Circle(U, (sqrt(2) / 2 * a)) → e_2
  48. Intersect(e_2, h_2, 2) → V
  49. Polygon(Q, R, V, U) → q3, q_3, r_3, v, u
  50. Point(Circle[W, a / 2]) → Z
  51. Segment(W, Z) → i_2
  52. Rotate(Z, ((-π)) / 2, W) → Z'
  53. Polygon(Z, W, Z') → t5, z', z_1, w
  54. Point(Circle[A_1, a]) → B_1
  55. Segment(A_1, B_1) → j_2
  56. Rotate(B_1, ((-π)) / 4, A_1) → C_1
  57. Rotate(A_1, π / 4, B_1) → D_1
  58. Ray(B_1, D_1) → m_2
  59. Ray(A_1, C_1) → a_2
  60. Intersect(m_2, a_2) → E_1
  61. Polygon(B_1, A_1, E_1) → t6, b_2, f_3, g_3
  62. If(o ≟ 1, (sqrt(2) / 32 * a), o ≟ 2, a / 32) → r_{4}

AI Drawing Prompt Reference

Draw a tangram set composed of seven pieces, including right triangles and a square. Start by constructing a circle with a given center, pick a point on it, draw a line through the center and that point, then construct a perpendicular line through the point to intersect another circle, forming the third vertex of a right isosceles triangle. Repeat similar steps to create a second congruent right triangle and a small square. Then, construct a smaller right triangle and a parallelogram via rotation. Finally, use rotations and intersections to build two larger triangles, and assemble all polygons into the complete tangram shape.
The prompt above was compiled from the original drawing commands and is for reference only.