四边形内三角形面积乘积不变性

GeoGebra 命令及参数

1. Polygon(A, B, C, D) → poly1, a, b, c, d
2. Segment(A, C) → f
3. Segment(D, B) → g
4. Intersect(f, g) → E
5. Polygon(A, E, D) → poly2, d_1, a_1, e
6. Polygon(A, B, E) → poly3, e_1, a_2, b_1
7. Polygon(B, C, E) → poly4, e_2, b_2, c_1
8. Polygon(D, E, C) → poly5, c_2, d_2, e_3