圆的切线构造与演示

GeoGebra 命令及参数

1. PointIn(e) → A
2. PointIn(e) → B
3. PointIn(e) → D
4. Line(A, B) → f
5. Polygon(A, C, B) → t1, b_1, a_1, c_1
6. Segment(B, C) → g
7. Segment(C, A) → h
8. Slope(f) → i
9. Textfield(k) → InputBox2
10. Textfield(j) → InputBox1
11. Mode(l1) → l2
12. If(Length[l2] ≟ 0, "You have no repeated digits!", "You have repeated digits.") → text5
13. Circle(D, A) → p
14. Segment(D, A) → q
15. Angle(B, A, D) → α
16. If(α ≟ pi / 2, "Line is tangent to circle.", "Line is not tangent to circle.") → text1
17. Textfield(s) → InputBox3
18. Textfield(t) → InputBox4
19. If(j / k ≟ i, "√", "X") → text6
20. If(Slope[q] ≟ s / t, "√", "X") → text7