Exterior Angles of Polygons Demo by Linda Bollman

Exterior Angles of Polygons Demo by Linda Bollman
Loading the math board and drawing, please wait…
2014-08-13 01:03
This example visually demonstrates the concept of exterior angles in polygons by simulating a car turning at each vertex, helping students grasp the relationship between exterior and interior angles. Key math concepts include angle measurement, polygon properties, and rotational symmetry. GeoGebra commands like Rotate, Polygon, Vector, and Angle are used to construct the dynamic model. Suitable for middle school and high school geometry instruction.

GeoGebra Commands & Parameters

  1. Rotate((x(P1) + (x(A) - x(E)) / Distance[E, A], y(P1) + (y(A) - y(E)) / Distance[E, A]), Min[Max[t - 1, 0], 1] * (180° - Angle[B, A, E]), P1) → P1'
  2. Rotate((x(P2) + (x(B) - x(A)) / Distance[A, B], y(P2) + (y(B) - y(A)) / Distance[A, B]), Min[Max[t - 3, 0], 1] * (180° - Angle[C, B, A]), P2) → P2'
  3. Rotate((x(P3) + (x(C) - x(B)) / Distance[B, C], y(P3) + (y(C) - y(B)) / Distance[B, C]), Min[Max[t - 5, 0], 1] * (180° - Angle[D, C, B]), P3) → P3'
  4. Rotate((x(P4) + (x(D) - x(C)) / Distance[C, D], y(P4) + (y(D) - y(C)) / Distance[C, D]), Min[Max[t - 7, 0], 1] * (180° - Angle[E, D, C]), P4) → P4'
  5. Rotate((x(P5) + (x(E) - x(D)) / Distance[E, D], y(P5) + (y(E) - y(D)) / Distance[E, D]), Min[Max[t - 9, 0], 1] * (180° - Angle[A, E, D]), P5) → P5'
  6. Polygon(E, A, B, C, D) → poly1, a_1, b_1, c_1, d_1, e_1
  7. If(t ≤ 2, P1, If[t ≤ 4, P2, If[t ≤ 6, P3, If[t ≤ 8, P4, If[t ≤ 10, P5, P6]]]]) → P
  8. If(t ≤ 2, P1', If[t ≤ 4, P2', If[t ≤ 6, P3', If[t ≤ 8, P4', If[t ≤ 10, P5', P6']]]]) → P'
  9. Vector(P, P') → u
  10. Angle(P1', P1, (x(P1) + (x(A) - x(E)) / Distance[E, A], y(P1) + (y(A) - y(E)) / Distance[E, A])) → α
  11. Angle(P2', P2, (x(P2) + (x(B) - x(A)) / Distance[A, B], y(P2) + (y(B) - y(A)) / Distance[A, B])) → β
  12. Angle(P3', P3, (x(P3) + (x(C) - x(B)) / Distance[B, C], y(P3) + (y(C) - y(B)) / Distance[B, C])) → γ
  13. Angle(P4', P4, (x(P4) + (x(D) - x(C)) / Distance[C, D], y(P4) + (y(D) - y(C)) / Distance[C, D])) → δ
  14. Angle(P5', P5, (x(P5) + (x(E) - x(D)) / Distance[E, D], y(P5) + (y(E) - y(D)) / Distance[E, D])) → ε
  15. OrthogonalLine(P, u) → f
  16. Point(f) → F
  17. Midpoint(F, P') → G
  18. Vector(G, P) → v
  19. Translate(P, v) → P'_1
  20. Translate(P', v) → P''
  21. Segment(A, (x(A) + (x(A) - x(E)) / Distance[E, A], y(A) + (y(A) - y(E)) / Distance[E, A])) → g
  22. Segment(B, (x(B) + (x(B) - x(A)) / Distance[A, B], y(B) + (y(B) - y(A)) / Distance[A, B])) → h
  23. Segment(C, (x(C) + (x(C) - x(B)) / Distance[B, C], y(C) + (y(C) - y(B)) / Distance[B, C])) → i
  24. Segment(D, (x(D) + (x(D) - x(C)) / Distance[C, D], y(D) + (y(D) - y(C)) / Distance[C, D])) → j
  25. Segment(E, (x(E) + (x(E) - x(D)) / Distance[D, E], y(E) + (y(E) - y(D)) / Distance[D, E])) → k
  26. Midpoint(a_1) → O
  27. Angle((x(A) + (x(A) - x(E)) / Distance[E, A], y(A) + (y(A) - y(E)) / Distance[E, A]), A, B) → a
  28. Angle((x(B) + (x(B) - x(A)) / Distance[A, B], y(B) + (y(B) - y(A)) / Distance[A, B]), B, C) → b
  29. Angle((x(C) + (x(C) - x(B)) / Distance[B, C], y(C) + (y(C) - y(B)) / Distance[B, C]), C, D) → c
  30. Angle((x(D) + (x(D) - x(C)) / Distance[C, D], y(D) + (y(D) - y(C)) / Distance[C, D]), D, E) → d
  31. Angle((x(E) + (x(E) - x(D)) / Distance[D, E], y(E) + (y(E) - y(D)) / Distance[D, E]), E, A) → e
  32. If((t ≥ 1) ∧ (t < 2), α, If[t ≥ 2, a, 0*°]) → α'
  33. If((t ≥ 3) ∧ (t < 4), β, If[t ≥ 4, b, 0*°]) → β'
  34. If((t ≥ 5) ∧ (t < 6), γ, If[t ≥ 6, c, 0*°]) → γ'
  35. If((t ≥ 7) ∧ (t < 8), δ, If[t ≥ 7, d, 0*°]) → δ'
  36. If((t ≥ 9) ∧ (t < 10), ε, If[t ≥ 9, e, 0*°]) → ε'

AI Drawing Prompt Reference

Draw a pentagon ABCDE and simulate a car turning at each vertex to show the exterior angles. First, draw the pentagon, then rotate an angle at each vertex to simulate the car turning, and display the degree of each exterior angle changing.
The prompt above was compiled from the original drawing commands and is for reference only.