抛物线的另一个定理

GeoGebra 命令及参数

1. Line(A, B) → d
2. Parabola(F, d) → c
3. Vertex(c) → V, , ,
4. Line(V, d) → g
5. Point(c) → P
6. OrthogonalLine(P, g) → h
7. Intersect(g, h) → F_1
8. Tangent(P, c) → i,
9. Intersect(g, i) → G
10. Intersect(d, h) → C
11. Circle(P, G) → d_1
12. Intersect(d_1, i, 2) → D
13. Segment(P, F_1) → j
14. Circle(F_1, (0.2 * j)) → e
15. Intersect(e, g, 2) → H
16. Intersect(e, j, 1) → I
17. Segment(F_1, C) → l
18. Circle(C, (0.2 * j)) → p
19. Intersect(p, d, 2) → J
20. Intersect(p, l, 1) → K
21. Intersect(p, d, 1) → L
22. CircleSector(C, K, L) → q
23. Dilate(P, If[0 < a ≤ 1, 1 - a, 0], C) → E'
24. Segment(P, E') → k
25. Rotate(q, If[1.5 < a ≤ 2.5, ((-(a - 1.5)) * π / 2), ((-π)) / 2], C) → q'
26. Dilate(C, If[3 < a ≤ 4, 4 - a, 0], F_1) → C'
27. Vector(C, C') → u
28. Translate(q', u) → q''
29. Dilate(P, If[4 < a ≤ 5, 5 - a, 0], G) → E'_1
30. Segment(P, E'_1) → t
31. Dilate(V, If[5 < a ≤ 6, 6 - a, 0], G) → V'
32. Segment(V, V') → m
33. Rotate(V, If[6 < a ≤ 7, ((a - 6) * π), π], G) → V'_1
34. Rotate(V', If[6 < a ≤ 7, ((a - 6) * π), π], G) → V''
35. Segment(V'_1, V'') → m'
36. CircleSector(C, L, K) → r
37. Rotate(r, If[1.5 < a ≤ 2.5, ((a - 1.5) * π / 2), π / 2], C) → r'
38. Translate(r', u) → r''