等角共轭：垂心、外心、内心

GeoGebra 命令及参数

1. Line(A, B) → f
2. Line(B, C) → g
3. Line(C, A) → h
4. Polygon(A, B, C) → t1, c, a, b
5. Line(A, P) → i
6. Line(B, P) → j
7. Line(P, C) → k
8. AngularBisector(B, A, C) → l
9. AngularBisector(A, C, B) → m
10. AngularBisector(C, B, A) → n
11. Mirror(i, l) → i'
12. Mirror(j, n) → j'
13. Mirror(k, m) → k'
14. Intersect(i', j') → P'
15. Intersect(l, m) → I
16. OrthogonalLine(A, g) → p
17. OrthogonalLine(B, h) → q
18. Intersect(p, q) → H
19. Center(Circle[A, B, C]) → O