Triangle Area by Åsmund Børsum

Triangle Area by Åsmund Børsum
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2013-01-02 19:48
This example demonstrates how to cover a triangle with integer unit squares to calculate its area. Key concepts include triangle area calculation and geometric construction. It uses commands like Circle, Point, Segment, Line, Polygon in GeoGebra. Suitable for middle school and above students to learn triangle area calculation.

GeoGebra Commands & Parameters

  1. Circle(A, Height) → c
  2. Circle(A, Base) → d
  3. Point(d) → B
  4. Segment(A, B) → e
  5. Line(A, B) → f
  6. OrthogonalLine(A, f) → g
  7. Intersect(c, g, 1) → C
  8. Tangent(C, c) → h, a
  9. Polygon(A, B, D) → P, d_1, a_1, b_1
  10. OrthogonalLine(D, f) → i
  11. Intersect(f, i) → E
  12. Segment(E, D) → j
  13. Segment(E, B) → k
  14. Midpoint(D, B) → F
  15. Midpoint(D, A) → G
  16. Point(a_1) → H
  17. Circle(B, H) → p
  18. Intersect(p, d_1, 1) → I
  19. OrthogonalLine(H, a_1) → l
  20. OrthogonalLine(I, d_1) → m
  21. Intersect(l, m) → J
  22. If(x(D) ≟ x(B), G) → K
  23. If(x(D) ≟ x(B), J) → L
  24. Segment(L, H) → n
  25. Segment(L, I) → q
  26. Rotate(A, Hint, K) → A'
  27. Rotate(B, Hint, K) → B'
  28. Rotate(D, Hint, K) → D'
  29. Polygon(A', B', D') → P', d', a', b'
  30. If(x(D) ≟ x(A), F) → M
  31. Point(b_1) → N
  32. Circle(A, N) → r
  33. Intersect(r, d_1, 1) → O
  34. OrthogonalLine(N, b_1) → s
  35. OrthogonalLine(O, d_1) → t
  36. Intersect(s, t) → Q
  37. If(x(D) ≟ x(A), Q) → R
  38. Segment(N, R) → c_1
  39. Segment(R, O) → e_1
  40. Rotate(A, (-Hint), M) → A'_1
  41. Rotate(B, (-Hint), M) → B'_1
  42. Rotate(D, (-Hint), M) → D'_1
  43. Polygon(A'_1, B'_1, D'_1) → P'_1, d'_1, a'_1, b'_1
  44. If(x(D) > x(B), G) → S
  45. Rotate(A, Hint, S) → A'_2
  46. Rotate(B, Hint, S) → B'_2
  47. Rotate(D, Hint, S) → D'_2
  48. Polygon(A'_2, B'_2, D'_2) → P'_2, d'_2, a'_2, b'_2
  49. If(x(D) < x(A), F) → T
  50. Rotate(A, (-Hint), T) → A'_3
  51. Rotate(B, (-Hint), T) → B'_3
  52. Rotate(D, (-Hint), T) → D'_3
  53. Polygon(A'_3, B'_3, D'_3) → P'_3, d'_3, a'_3, b'_3
  54. If((x(D) > x(A)) ∧ (x(D) < x(B)), F) → U
  55. Rotate(A, (-Hint), U) → A'_4
  56. Rotate(B, (-Hint), U) → B'_4
  57. Rotate(D, (-Hint), U) → D'_4
  58. Polygon(A'_4, B'_4, D'_4) → P'_4, d'_4, a'_4, b'_4
  59. Midpoint(D, E) → V
  60. Midpoint(A, B) → W
  61. Polygon(Z_1, A, D) → Mangekant1, d_2, z_1, a_2
  62. Midpoint(a_2) → Z
  63. Rotate(D, Hint, Z) → A_2
  64. Rotate(A, Hint, Z) → A_3
  65. Rotate(Z_1, Hint, Z) → A_1
  66. Polygon(A_2, A_3, A_1) → Mangekant2, a_3, a_4, a_5

AI Drawing Prompt Reference

Draw a triangle ABC and cover it with integer unit squares to calculate its area. Start by drawing the base AB, then construct the perpendicular bisector of the base to find the vertex C. Construct the height of the triangle, use midpoints and perpendicular lines to create auxiliary lines, and finally use rotation and symmetry to construct the grid of squares covering the triangle.
The prompt above was compiled from the original drawing commands and is for reference only.