Kiepert 抛物线的中心

GeoGebra 命令及参数

1. Line(A, B) → a
2. Line(B, C) → b
3. Line(C, A) → c
4. Circle(A, B, C) → d
5. Center(d) → O
6. Centroid(Polygon[A, B, C]) → G
7. Mirror(G, c) → G'
8. Mirror(G, a) → G'_1
9. Mirror(G, b) → G'_2
10. LineBisector(G'_1, G') → e
11. LineBisector(G', G'_2) → f
12. Intersect(e, f) → K
13. Line(K, O) → g
14. Point(g) → P
15. Mirror(P, a) → P'_3
16. Mirror(P, c) → P'_1
17. Mirror(P, b) → P'_2
18. LineBisector(P'_3, P'_1) → h
19. LineBisector(P'_1, P'_2) → i
20. Intersect(h, i) → P'
21. Locus(P', P) → loc1
22. Polygon(A, B, C) → poly1, c_1, a_1, b_1
23. OrthogonalLine(A, b) → j
24. OrthogonalLine(B, c) → k
25. OrthogonalLine(C, a) → l
26. Intersect(a, l) → D
27. Intersect(c, k) → E
28. Intersect(b, j) → F
29. Polygon(D, E, F) → poly2, f_1, d_1, e_1
30. Intersect(l, j) → H
31. Tool2(A, D, E) → m
32. Tool2(B, D, F) → n
33. Tool2(F, E, C) → p
34. Intersect(m, n) → K_1