抛物线的切线与光线 by Amarzaya

GeoGebra 命令及参数

1. Parabola(F_2, x = 0) → d
2. Intersect(d, j) → H_1,
3. If(t ≤ 1, H_1) → H
4. Point(d) → B
5. Vector(H_1, F_2) → v
6. Vector(E, H) → u
7. If(t ≤ 1, ((x(u) * t) + x(E), y(E))) → C
8. If(t ≥ 1, Tangent[H, d]) → f
9. Angle(f, Line[F_2, B]) → α
10. If(t ≥ 1, ((x(v) * (t - 1)) + x(H_1), (y(v) * (t - 1)) + y(H_1))) → D
11. Point(f) → F
12. Point(f) → G
13. If(t ≟ 2, Angle[G, B, F_1]) → γ
14. Angle(F_2, B, F) → β
15. Vector(E, C) → g
16. Vector(H_1, D) → h
17. If(t ≥ 1, Segment[E, H_1]) → i
18. If(t ≟ 2, Tangent[H_1, d]) → l