单位圆的构建

GeoGebra 命令及参数

1. Intersect(xAxis, yAxis) → A
2. Circle(A, 100) → c
3. Intersect(c, xAxis, 2) → B
4. Intersect(c, yAxis, 2) → C
5. Point(c) → D
6. Segment(A, D) → a
7. Segment(A, B) → b
8. Line(A, B) → d
9. Line(A, C) → e
10. OrthogonalLine(D, b) → f
11. OrthogonalLine(D, e) → g
12. Intersect(g, e) → E
13. Intersect(g, f) → F
14. Intersect(d, xAxis) → G
15. Intersect(d, xAxis) → H
16. Intersect(d, b) → I
17. Intersect(f, d) → J
18. Segment(D, J) → h
19. Angle(B, A, D) → α