三角形的外接圆

GeoGebra 命令及参数

1. Segment(A, B) → f
2. Segment(B, C) → g
3. Segment(C, A) → h
4. Midpoint(A, C) → M
5. Midpoint(C, B) → L
6. Midpoint(B, A) → N
7. Line(A, C) → l
8. Line(C, B) → m
9. Line(B, A) → n
10. OrthogonalLine(N, n) → i
11. OrthogonalLine(M, l) → j
12. OrthogonalLine(L, m) → k
13. Intersect(i, j) → O
14. Intersect(j, m) → D
15. Intersect(k, l) → E
16. If(a < 1, Segment[L, (x(L) + (a * (x(E) - x(L))), y(L) + (a * (y(E) - y(L))))], Segment[L, E]) → q
17. Intersect(m, i) → F
18. If(2 < a < 3, Segment[N, (x(N) + ((a - 2) * (x(F) - x(N))), y(N) + ((a - 2) * (y(F) - y(N))))], a ≥ 3, Segment[N, F]) → r
19. If(1 < a < 2, Segment[M, (x(M) + ((a - 1) * (x(D) - x(M))), y(M) + ((a - 1) * (y(D) - y(M))))], a ≥ 2, Segment[M, D]) → p
20. If(3 < a < 4, Circle[O, (x(O) + ((a - 3) * (x(A) - x(O))), y(O) + ((a - 3) * (y(A) - y(O))))], a ≟ 4, Circle[O, A]) → c