平行四边形的证明

GeoGebra 命令及参数

1. Segment(A, B) → f
2. Segment(B, C) → g
3. Line(C, f) → h
4. Line(A, g) → i
5. Intersect(h, i) → D
6. Polygon(A, B, C, D) → q1, a, b, c, d
7. Segment(E, F) → j
8. Segment(D, B) → n_1
9. Segment(A, C) → p
10. Intersect(n_1, p) → X
11. Line(B, C) → i'
12. Line(A, B) → h'
13. Line(E, F) → l'
14. OrthogonalLine(F, l') → k
15. Point(k) → G
16. Line(G, l') → l
17. Line(E, k) → m
18. Intersect(l, m) → H
19. Polygon(E, F, G, H) → q2, e, f_1, g_1, h_1
20. Segment(E, G) → n
21. Segment(F, H) → q
22. Intersect(n, q) → Y