利用三角函数构造圆的面积

GeoGebra 命令及参数

1. Sequence(Rotate[A, ((2 * pi / n) * i), B], i, 0, n) → list1
2. Sequence(Segment[Element[list1, i], Element[list1, i + 1]], i, 0, n) → list2
3. Polygon(A, B, Element[list1, 2]) → poly1, b, a_1, b_1
4. OrthogonalLine(B, b_1) → d
5. Intersect(d, b_1) → C
6. Segment(B, C) → e
7. Angle(B, C, A) → α
8. Rotate(A, (2 * pi / n), B) → A'
9. Angle(A, B, A') → θ
10. Circle(B, 2) → f
11. Segment(A, C) → g
12. Polygon(list1) → poly2
13. Textfield(s) → InputBox1