丹德林球（Dandelin's Spheres）的圆锥截面演示

GeoGebra 命令及参数

1. Line((0, 0, -3), (0, 0, r_2)) → zg
2. Cone((0, 0, -3), (0, 0, r_2), r_1) → kg, c, a
3. IntersectPath(E_0, kg) → d
4. Focus(d) → F_1, F_2
5. OrthogonalLine(F_1, d) → a_1
6. Corner(d) → A, B, C, D
7. Segment((0, 0, -3), (0, 0, r_2)) → za
8. Intersect(a_1, zg) → C_1
9. Sphere(C_1, F_1) → Dk_1
10. OrthogonalLine(F_2, d) → a_2
11. Intersect(a_2, zg) → C_2
12. Sphere(C_2, F_2) → Dk_2
13. Point(d) → P
14. Segment(C_1, F_1) → cf_1
15. Segment(C_2, F_2) → cf_2
16. Ray(Z, Q) → zq
17. OrthogonalLine(C_2, zq, space) → sc_2
18. Intersect(zq, sc_2) → Bk_2
19. Circle((0, 0, z(Bk_2)), x(Bk_2), space) → kr_2
20. Circle(Bk_{2c}, Bk_{2b}, Bk_2) → e_2
21. OrthogonalLine(C_1, zq, space) → sc_1
22. Intersect(zq, sc_1) → Bk_1
23. Circle(Bk_{1c}, Bk_{1b}, Bk_1) → e_1
24. Intersect(zq, c) → E,
25. Ray(Z, P) → zp
26. Intersect(zp, c) → F,
27. IntersectPath(E_0, E_1) → b
28. OrthogonalLine(P_1, b, space) → e
29. Intersect(b, e) → L
30. Line(L, P) → f
31. Segment(P, P_1) → s_{01}
32. Segment(P_1, L) → s_{02}
33. Segment((0, 0, z(Bk_1)), P_1) → s_{m2}
34. Intersect(s_{m2}, e_1) → P_3,