余弦定理 - 求角度

GeoGebra 命令及参数

1. Point(Circle[R, c]) → Q
2. Circle(Q, a) → d_1
3. Circle(R, b) → c_1
4. Intersect(c_1, d_1) → P, B_1, ,
5. Angle(P, Q, R) → δ
6. Angle(Q, R, P) → α_1
7. Segment(P, R) → b_2
8. Segment(R, Q) → c_2
9. Segment(Q, P) → a_2
10. Midpoint(a_2) → A'
11. Midpoint(c_2) → C'
12. Midpoint(b_2) → B'
13. Midpoint(C', A') → D
14. Midpoint(C', Q) → E
15. Midpoint(A', Q) → F
16. Midpoint(F, E) → G
17. Midpoint(R, B') → H
18. Midpoint(C', R) → I
19. Midpoint(I, H) → J
20. Midpoint(B', P) → K
21. Midpoint(A', P) → L
22. Midpoint(B', A') → M
23. Midpoint(K, L) → N
24. Midpoint(N, M) → O
25. If(CosA < 0, "-", "") → signCosA
26. If(CosB < 0, "-", "") → signCosB
27. Segment(R, Q) → a_1
28. Segment(R, P) → b_1
29. Segment(P, Q) → e_1
30. Angle(R, P, Q) → ε
31. Vector(R, A') → u
32. Vector(P, C') → w
33. Vector(Q, B') → v