梯形面积的计算方法

GeoGebra 命令及参数

1. Segment(A, B) → a
2. Line(C, a) → b
3. Segment(C, A) → c
4. Point(b) → D
5. Segment(D, B) → d
6. Segment(C, D) → e
7. Midpoint(d) → E
8. Polygon(C, A, B, D) → poly1, c_1, a_1, b_1, d_1
9. Rotate(C, 180*°, E) → C'
10. Rotate(A, 180*°, E) → A'
11. Rotate(B, 180*°, E) → B'
12. Rotate(D, 180*°, E) → D'
13. Polygon(C', A', B', D') → poly1', c', a', b', d'
14. PointIn(poly1) → Pointpoly1
15. PointIn(poly1') → Pointpoly1'
16. Line(C, e) → f
17. OrthogonalLine(A, f) → g
18. Intersect(f, g) → F
19. Segment(F, A) → h
20. Segment(F, C) → i
21. Angle(A, F, C) → α