无字证明：用对称变换展示几何不等式关系

GeoGebra 命令及参数

1. Point(yAxis) → A
2. Point(xAxis) → B
3. Point(xAxis) → D
4. Polygon(A, B, C) → t1, c, a, b
5. Polygon(A, D, C) → t2, c_1, a_1, d
6. PointIn(t1) → E
7. Mirror(E, zAxis) → E'
8. Rotate(E, 90°, zAxis) → E'_1
9. Mirror(E'_1, zAxis) → F
10. Line(E, c) → f
11. Line(F, a) → g
12. Line(E', a_1) → h
13. Line(E'_1, c_1) → i
14. Intersect(f, i) → G
15. Intersect(f, g) → H
16. Intersect(h, g) → I
17. Intersect(h, i) → J
18. Polygon(A, G, E, F, I, C, B) → poly1, a_2, g_1, e, f_1, i_1, c_2, b_1
19. Polygon(A, G, E'_1, E', I, C, D) → poly2, a_3, g_2, e'_1, e', i_2, c_3, d_1
20. Rotate(poly2, α, xAxis) → poly2'
21. Rotate(E', α, xAxis) → E''
22. Rotate(E'_1, α, xAxis) → K
23. Segment(F, E'') → j
24. Segment(E, K) → k