Isosceles Triangle Quick Construction Technique

Isosceles Triangle Quick Construction Technique
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2017-02-17 21:41
This example demonstrates how to construct an isosceles triangle quickly using compass and straightedge. Core math concepts include circles, intersections, rotations, and geometric transformations. Construction highlights involve GeoGebra commands like Circle, Intersect, Rotate, Dilate, combined with objects such as Points, Segments, Angles, and Midpoints. Suitable for middle school and above, for learning geometric construction techniques and transformation methods.

GeoGebra Commands & Parameters

  1. Circle(A, B) → c
  2. Intersect(c, q) → O, P
  3. CircleArc(A, O, P) → d
  4. Point(d) → C
  5. CircleArc(A, C, P) → e
  6. Point(e) → D
  7. Dilate(A, If[0 < j ≤ 1, 1 - j, 0], C) → A'
  8. Segment(A, A') → a
  9. Angle(C, A, D) → α
  10. Rotate(A, If[1 < j ≤ 2, ((j - 1) * α), α], A) → A'_1
  11. Rotate(A', If[1 < j ≤ 2, ((j - 1) * α), α], A) → A''
  12. Segment(A'_1, A'') → a'
  13. Segment(A, C) → b
  14. Segment(C, D) → f
  15. Segment(D, A) → g
  16. Midpoint(f) → E
  17. Segment(A, E) → h
  18. Midpoint(h) → F
  19. Segment(A, F) → i
  20. Segment(F, E) → k
  21. Circle(A, (0.35 * i)) → p
  22. Circle(E, (0.15 * Distance[D, E])) → r
  23. Intersect(r, f, 2) → G
  24. Intersect(r, h, 1) → H
  25. Intersect(r, f, 1) → I
  26. Intersect(p, b, 1) → J
  27. Intersect(p, h, 1) → K
  28. Intersect(p, g, 1) → L
  29. Circle(A, B) → c_1
  30. Dilate(C, If[2 < j ≤ 3, 3 - j, 0], D) → C'
  31. Segment(C, C') → l
  32. Polygon(C, D, A) → poly1, a_1, c_2, d_1
  33. Circle(C, (0.2 * Distance[D, E])) → e_1
  34. Intersect(e_1, b) → M,
  35. Intersect(e_1, f) → N,
  36. Dilate(A, If[3 < j ≤ 4, 4 - j, 0], F) → A'_2
  37. Dilate(F, If[5 < j ≤ 6, 6 - j, 0], E) → F'
  38. Dilate(E, If[6 < j ≤ 7, 7 - j, 0], D) → E'
  39. Rotate(E, If[7 < j ≤ 8, ((j - 7) * π), 3.141592653589793], E) → E'_1
  40. Rotate(E', If[7 < j ≤ 8, ((j - 7) * π), 3.141592653589793], E) → E''
  41. Dilate(C, If[9 < j ≤ 10, 10 - j, 0], D) → C'_1
  42. Vector(C, C'_1) → u
  43. Angle(E, C, A) → β
  44. CircleArc(A, C, A'') → s_1