空心碗（圆盘环形）质心的几何求法

GeoGebra 命令及参数

1. Surface(f, θ, xAxis) → a
2. Surface(g, θ, xAxis) → b
3. Circle(xAxis, A) → c
4. Circle(xAxis, B) → d
5. Segment(B, A) → h
6. Segment(I, J) → l
7. Semicircle(J, L) → p
8. Segment(J, L) → m
9. Ray(I, M) → n
10. Point(n) → K
11. Vector(I, K) → u
12. Angle(O, I, M) → α
13. Rotate(p, (-α), I) → p'
14. Rotate(I, (-α), I) → I'
15. Rotate(J, (-α), I) → J'
16. Segment(I', J') → l'
17. Rotate(O, (-α), I) → O'
18. Rotate(M, (-α), I) → G'
19. Rotate(J, (-α), I) → J'_1
20. Rotate(L, (-α), I) → L'
21. Segment(J'_1, L') → m'
22. Segment(O', G') → q
23. Angle(G', O', I) → β
24. Rotate(u, (-α), I) → u'
25. Angle(O', I, O) → γ
26. OrthogonalLine(I, l') → s
27. OrthogonalLine(O', m') → t
28. OrthogonalLine(J', l') → f_1
29. Point(s) → N
30. OrthogonalLine(N, s) → g_1
31. Intersect(g_1, f_1) → P
32. Intersect(g_1, t) → Q
33. Vector(N, P) → v
34. Vector(P, N) → w
35. Vector(P, Q) → u_1
36. Vector(Q, P) → v_1
37. Midpoint(N, P) → R
38. Midpoint(P, Q) → S
39. Midpoint(O', G') → T