圆的切线性质探索

GeoGebra 命令及参数

1. Circle(O, B_1) → c
2. Segment(O, B_1) → a
3. PointIn(b) → E
4. Tangent(E, c) → d, e
5. Intersect(c, e, 1) → B
6. Intersect(c, d, 1) → A
7. Ray(E, A) → f
8. Ray(E, B) → g
9. Segment(O, A) → h
10. Segment(O, B) → i
11. Dilate(O, If[0 < j ≤ 1, 1 - j, 0], A) → A'
12. Dilate(O, If[0 < j ≤ 1, 1 - j, 0], B) → A'_1
13. Segment(O, A') → k
14. Segment(O, A'_1) → l
15. Angle(E, B, O) → α
16. Angle(O, A, E) → β
17. Circle(A, (0.25 * a)) → p
18. Circle(B, (0.25 * a)) → q
19. Intersect(p, h, 1) → F
20. Intersect(q, i, 1) → G
21. Intersect(p, f) → H, I
22. Intersect(q, g) → J, K
23. Circle(O, B_1) → t
24. Dilate(O, If[1.3 < j ≤ 2.3, 2.3 - j, 0], E) → C'
25. Polygon(B, E, O) → poly1, a_1, d_1, c_1
26. Angle(A, E, B) → γ
27. Rotate(B, If[5 < j ≤ 6, ((j - 5) * ((2 * π) - γ)), (2 * π) - γ], E) → D'_1
28. Rotate(E, If[5 < j ≤ 6, ((j - 5) * ((2 * π) - γ)), (2 * π) - γ], E) → C'_1
29. Segment(E, A) → n
30. Segment(E, B) → b_1
31. Polygon(O, E, A) → poly2, e_1, a_2, c_2
32. Segment(O, C') → f_1
33. Rotate(E, If[5 < j ≤ 6, ((j - 5) * (-γ)), (-γ)], E) → C'_2
34. Rotate(B, If[2.5 < j ≤ 3.5, ((j - 2.5) * (-γ)), (-γ)], E) → D'
35. Segment(C'_2, D') → h_1