正弦定理的另一种证明方法

GeoGebra 命令及参数

1. Intersect(xAxis, yAxis) → O
2. Circle(O, 1) → d
3. Sequence((cos(u), sin(u)), u, 0, (2 * π) - π / 90, π / 90) → l1
4. Point(l1) → B
5. Point(l1) → C
6. Point(l1) → A
7. Polygon(B, A, C) → t1, c, b, a
8. Angle(B, A, C) → α
9. Angle(A, C, B) → β
10. Angle(C, B, A) → γ
11. Angle(B, A, C) → δ
12. Angle(A, C, B) → ε
13. Angle(C, B, A) → ζ
14. Midpoint(B, O) → E
15. Midpoint(O, C) → F
16. Midpoint(B, O) → G
17. Midpoint(O, A) → H
18. Midpoint(C, O) → I
19. Midpoint(O, A) → J