平行四边形面积计算 by Sean Kelleher

GeoGebra 命令及参数

1. Segment(A, B) → base
2. Segment(A, C) → g
3. Line(C, base) → h
4. Line(B, g) → i
5. Intersect(h, i) → D
6. OrthogonalLine(B, base) → j
7. Intersect(h, j) → E
8. Polygon(E, B, D) → t1, d, e, b
9. Segment(D, C) → k
10. Point(k) → F
11. Vector(D, F) → u
12. Translate(E, u) → E'
13. Translate(B, u) → B'
14. Translate(D, u) → D'
15. Polygon(E', B', D') → t1', height, width, b'
16. Polygon(A, B, E, C) → q1, a, b_1, e_1, c
17. Segment(C, E) → l
18. Angle(E, B, A) → α
19. Angle(D', E', B') → β