余弦定理 - 求边长

GeoGebra 命令及参数

1. Line(R, orientation) → z
2. Circle(R, QR) → v
3. Intersect(v, z) → P'', Q
4. Rotate(Q, angleR°, R) → P'
5. Angle(Q, R, P') → ρ
6. Line(P', R) → w
7. Circle(R, PR) → u
8. Segment(R, Q) → p
9. Intersect(u, w) → P, P'''
10. Segment(R, P) → q
11. Segment(P, Q) → r
12. Rotate(Q, 180° - angleR°, R) → Q'
13. Midpoint(P, Q) → M_1
14. Midpoint(R, P) → M_2
15. Midpoint(R, Q) → M_3
16. Vector(R, M_1) → c
17. Vector(Q, M_2) → a
18. Vector(P, M_3) → b
19. Midpoint(M_2, R) → M''_2
20. Midpoint(M_3, R) → M''_3
21. Midpoint(M''_2, M''_3) → M_4
22. Distance(P, Q) → PQ