使用配方法推导二次公式

GeoGebra 命令及参数

1. Polygon(A_1, A_2, 4) → poly1, b_1, b, c, d, A_3, A_4
2. Ray(A_2, A_2 + Vector[A_1, A_2]) → r
3. Point(r) → B_1
4. OrthogonalLine(B_1, b_1) → e
5. Line(A_4, A_3) → f
6. Intersect(e, f) → B_4
7. If(a < 25, 0, If[a ≤ 125, (pi * (a - 25) / 100)]) → a_1
8. OrthogonalLine(B_2, b_1) → g
9. Intersect(f, g) → B_3
10. Rotate(B_3, a_1, B_4) → B_3'
11. Rotate(B_1, a_1, B_4) → B_1'
12. Rotate(B_2, a_1, B_4) → B_2'
13. Polygon(B_4, B_1', B_2', B_3') → poly2, b_4, b_1', b_2', b_3'
14. If(a ≥ 175, 1.5707963267948966, If[125 < a, (pi / 2 * (a - 125) / 50)]) → a_2
15. Rotate(B_4, a_2, A_3) → B_4'
16. Rotate(C_1, a_2, A_3) → C_1'
17. Rotate(C_2, a_2, A_3) → C_2'
18. Polygon(A_3, B_4', C_1', C_2') → poly3, a_3, b_4', c_1', c_2'
19. Rotate(B_3, 90°, B_4) → D
20. If(a ≥ 175, Polygon[A_3, B_4, D, B_4']) → poly4
21. Polygon(A_2, B_1, B_4, A_3) → poly5, a_4, b_2, b_3, a_5
22. Polygon(T_1, T_2, T_3, T_4) → polyTbox, a_6, b_5, c_1, e_1
23. Midpoint(b_3) → A
24. Midpoint(a_4) → B
25. Midpoint(b_1) → C
26. Midpoint(d) → E
27. Midpoint(c_1') → F
28. Midpoint(b_1') → G
29. Vector(H, I) → u