平行四边形面积 by Kim Kelly

GeoGebra 命令及参数

1. Line(A, B) → f
2. Point(f) → heightPOINT
3. OrthogonalLine(heightPOINT, f) → g
4. Line(B, D) → h
5. Line(A, h) → i
6. Line(D, f) → j
7. Intersect(i, j) → E
8. Polygon(E, D, B, A) → parallelogram, parallD, parallC, parallB, parallA
9. Intersect(g, j) → F
10. Segment(heightPOINT, F) → parallHEIGHT
11. Angle(parallHEIGHT, parallB) → perpHEIGHT
12. Vector(B, A) → u
13. Polygon(B, D, F, heightPOINT) → willSLIDE, willC, willD, willA, willB
14. Translate(B, u) → B'
15. Translate(D, u) → D'
16. Translate(F, u) → F'
17. Translate(heightPOINT, u) → C'
18. Polygon(B', D', F', C') → slid, slidC, slidD, slidA, slidB
19. Polygon(D, F, heightPOINT, B) → HIDEpoly, hideD, hideA, hideB, hideC