平行线的内错角

GeoGebra 命令及参数

1. Line(A, B) → a
2. Line(C, a) → b
3. Line(D, E) → c
4. Intersect(a, c) → F
5. Intersect(b, c) → G
6. Circle(F, 1) → d
7. Intersect(d, a, 2) → H
8. Intersect(d, c, 1) → I
9. Circle(G, 1) → e
10. Segment(G, F) → f
11. Point(f) → L
12. Circle(L, 1) → g
13. Line(H, c) → i
14. Vector(F, L) → u
15. Translate(I, u) → I'
16. Translate(H, u) → H'
17. Angle(H', L, I') → β
18. Intersect(d, a, 1) → H''
19. Intersect(d, c, 2) → I''
20. Angle(I'', F, H'') → α