已知顶点与焦点求抛物线方程的GeoGebra范例

GeoGebra 命令及参数

1. Random(0, 1) → choice
2. RandomElement(Union[Sequence[i, i, -6, -0.5, 0.5], Sequence[i, i, 0.5, 6, 0.5]]) → j_1
3. Random(-8, 8) → e_1
4. Sequence(i, i, -10, -1, 1) → l1
5. Sequence(i, i, 1, 10, 1) → l2
6. Union(l1, l2) → l3
7. RandomElement(l3) → i_1
8. Point(Ray[A + (0, 1), A + (0, 2)]) → H
9. Distance(A, H) → c_1
10. Point(Ray[A + (1, 0), A + (2, 0)]) → E
11. Distance(A, E) → d_1
12. Point(Segment[(h + 1, y(C) + 10), (h + 1, y(C) - 10)]) → D
13. Line(A, B) → f
14. Vector(A, C) → u
15. Polygon(A, C, B) → t1, b, a_1, c
16. Segment(A, C) → h_{1}
17. Vector((h, 0), A) → w
18. Vector((0, 0), (h, 0)) → j
19. Distance(A, E) → n
20. Vector(A, E) → v
21. Point(p) → F
22. Intersect(eq1, q) → G
23. Polygon(A, G, F) → t2, f_1, a_2, g_1
24. Segment(F, A) → r
25. Segment(A, G) → s
26. Segment(G, F) → t
27. Angle(A, G, F) → α
28. RotateText(text18, pi / 2) → text20
29. RotateText(text19, pi / 2) → text21
30. Vector(A, H) → u_1
31. RandomElement(l3) → k_1
32. If(e_1 < 0, (x + e_1)^(2), (x - e_1)^(2)) → p_1
33. If(e_1 < 0, text5, e_1 > 0, text4, text9) → text8
34. If(j_1 < 0, text7, j_1 > 0, text6, text10) → text11
35. If(choice ≟ 0, (x - e_1)^(2) = (r_1 * (y - i_1)), (y - i_1)^(2) = (r_1 * (x - e_1))) → eq2
36. Center(eq2) → I
37. Vertex(eq2) → J, K, L, M
38. Textfield(eq3) → InputBox1
39. Focus(eq2) → N,
40. Directrix(eq2) → s_1,