梯形面积公式推导演示

GeoGebra 命令及参数

1. Segment(A, B) → a
2. Line(C, a) → b
3. Point(b) → D
4. Polygon(A, B, D, C) → poly1, a_1, b_1, d, c
5. Line(A, B) → e
6. Point(b) → E
7. OrthogonalLine(E, b) → f
8. Intersect(e, f) → F
9. LineBisector(E, F) → g
10. Intersect(g, b_1) → G
11. Intersect(g, c) → H
12. Polygon(C, D, G, H) → poly2, c_1, d_1, g_1, h
13. Rotate(C, (-180)° * i, G) → C'
14. Rotate(D, (-180)° * i, G) → D'
15. Rotate(G, (-180)° * i, G) → G'
16. Rotate(H, (-180)° * i, G) → H'
17. Polygon(C', D', G', H') → poly2', c', d', g', h'
18. Segment(H, G) → j
19. Polygon(H, G, B, A) → poly3, h_1, g_2, b_2, a_2
20. Segment(A, C') → k
21. Segment(A, B) → l
22. Segment(C', D') → m
23. Segment(C, D) → n
24. LineBisector(C, D) → p
25. Intersect(p, n) → I
26. Intersect(p, a) → J
27. Segment(I, J) → q
28. Intersect(j, q) → K
29. Segment(K, J) → r