椭圆、双曲线与圆的包络线

GeoGebra 命令及参数

1. Polygon({(-12, -4.5), (13, -4.5), (13, 8.5), (-12, 8.5)}) → peep
2. Circle(O, 8) → c
3. Point(c) → A
4. Segment((-14, 0), (14, 0)) → domF
5. Point(domF) → F
6. Segment(F, A) → g
7. LineBisector(g) → envel
8. Intersect(envel, g) → I
9. Segment(F, I) → f
10. Segment(I, A) → h
11. Rotate(F, 90°, I) → F'
12. Angle(F, I, F') → α
13. Tangent(A, c) → tgA,
14. OrthogonalLine(A, tgA) → normA
15. Intersect(envel, normA) → E
16. Angle(tgA, normA) → β
17. Hyperbola(F, O, Radius[c] / 2) → ip
18. Ellipse(F, O, Radius[c] / 2) → d