圆外一点的切线

GeoGebra 命令及参数

1. Circle(A, 4) → c
2. Segment(A, B) → f
3. LineBisector(A, B) → g
4. Intersect(f, g) → C
5. Circle(C, Segment[B, C]) → d
6. Intersect(c, d) → D, E, ,
7. Segment(D, B) → h
8. Segment(E, B) → i
9. Segment(D, A) → j
10. Segment(A, E) → k
11. Angle(A, D, B) → α
12. Angle(B, E, A) → β
13. Angle(D, B, A) → γ
14. Angle(A, B, E) → δ
15. Distance(D, B) → distanceDB
16. Midpoint(D, B) →
17. Distance(B, E) → distanceBE
18. Midpoint(B, E) →