平行四边形面积演示 by Malin Christersson

GeoGebra 命令及参数

1. Line(A, B) → l1_1
2. Distance(A, B) → distAB
3. Line(C, l1_1) → l1_2
4. Line(C, B) → l2_1
5. OrthogonalLine(C, l2_1) → b
6. OrthogonalLine(B, l2_1) → ba
7. Line(A, l2_1) → l2_2
8. Intersect(l2_2, b) → CA
9. Intersect(l2_2, ba) → BA
10. Intersect(l1_2, l2_2) → D
11. OrthogonalLine(D, l1_2) → da
12. Intersect(l1_1, da) → DA
13. Distance(A, DA) → distAA'
14. OrthogonalLine(C, l1_2) → a
15. Intersect(l1_1, a) → CB
16. If(distAA' ≤ distAB, Polygon[A, DA, D]) → triangle1
17. Vector(A, B) → u
18. Translate(triangle1, u) → triangle1'
19. If(distAA' > distAB, Polygon[A, B, BA]) → triangle2
20. Vector(A, D) → v
21. Translate(triangle2, v) → triangle2'
22. If(distAA' > distAB, If[Distance[D, BA] < Distance[A, D], Polygon[BA, B, C, D], Polygon[C, CA, A, B]]) → quadri2
23. If(distAA' ≤ distAB, If[Distance[B, DA] ≥ Distance[B, A], Polygon[C, CB, A, D], Polygon[D, DA, B, C]]) → quadri1
24. If(Distance[B, DA] ≥ Distance[B, A], CB, DA) → A'
25. Polygon(C, D, A, B) → poly1, c, d, a_1, b_1