四边形外角和探索活动

GeoGebra 命令及参数

1. Rotate(A, (a * π / 180), B) → A'
2. Angle(A, B, A') → α
3. Ray(B, A') → f
4. Segment(B, A) → g
5. Point(f) → C
6. Angle(B, C, A) → β
7. Rotate(B, γ, C) → B'
8. Angle(B, C, B') → δ
9. Ray(C, B') → h
10. Point(h) → D
11. Ray(D, A) → i
12. Segment(A, B) → j
13. Segment(B, C) → k
14. Segment(C, D) → l
15. Segment(D, A) → m
16. Min({j, k, l, m}) → b
17. Ray(A, B) → n
18. Ray(B, C) → p
19. Circle(B, (0.25 * b)) → c
20. Intersect(c, n, 2) → E
21. Intersect(c, p, 1) → F
22. Circle(C, (0.25 * b)) → d
23. Circle(D, (0.25 * b)) → e
24. Circle(A, (0.25 * b)) → q
25. Intersect(d, h, 1) → G
26. Intersect(d, p, 2) → H
27. Intersect(e, i, 1) → I
28. Intersect(e, h, 2) → J
29. Intersect(q, n, 1) → K
30. Intersect(q, i, 2) → L
31. CircleSector(B, F, E) → r
32. CircleSector(C, G, H) → s
33. CircleSector(D, I, J) → t
34. CircleSector(A, K, L) → c_1
35. Angle(C, D, A) → ε
36. Line(B, A) → f_1
37. Dilate(A, If[0 < u ≤ 1, 1 - u, 0], B) → A'_1
38. Vector(A, A'_1) → v
39. Translate(c_1, v) → d_1
40. Dilate(B, If[1 < u ≤ 2, 2 - u, 0], C) → B'_1
41. Vector(B, B'_1) → w
42. Translate(d_1, w) → e_1
43. Translate(r, w) → r'
44. Dilate(C, If[2 < u ≤ 3, 3 - u, 0], D) → C'
45. Vector(C, C') → u_1
46. Translate(r', u_1) → r''
47. Translate(s, u_1) → s'
48. Translate(e_1, u_1) → g_1
49. Polygon(B, A, D, C) → poly1, b_1, a_1, d_2, c_2