筝形面积 by Beverly Heigre

GeoGebra 命令及参数

1. Midpoint(A, B) → C
2. Segment(A, B) → a
3. OrthogonalLine(C, a) → b
4. Point(b) → D
5. Segment(B, D) → e
6. Midpoint(e) → J
7. Point(b) → E
8. Segment(D, E) → c
9. Segment(A, D) → d
10. Segment(B, E) → f
11. Segment(A, E) → g
12. Polygon(D, C, B) → poly1, b_1, d_1, c_1
13. Polygon(C, B, E) → poly2, e_1, c_2, b_2
14. Midpoint(f) → I
15. Rotate(D, α, J) → D'_1
16. Rotate(C, α, J) → C'
17. Rotate(B, α, J) → B'
18. Polygon(D'_1, C', B') → poly1', b', d'_1, c'
19. Rotate(C, α, I) → C'_1
20. Rotate(B, α, I) → B'_1
21. Rotate(E, α, I) → E'_1
22. Polygon(C'_1, B'_1, E'_1) → poly2', e'_1, c'_1, b'_1
23. Polygon(A, D, C) → poly3, c_3, a_1, d_2
24. Polygon(A, C, E) → poly4, e_2, a_2, c_4
25. Rotate(D, α, D) → D'
26. Rotate(E, α, E) → E'