旋转中的角度和定理

GeoGebra 命令及参数

1. Polygon(A, B, C) → poly1, c, a, b
2. Angle(B, A, C) → α
3. Angle(C, B, A) → β
4. Angle(A, C, B) → γ
5. Midpoint(A, C) → D
6. Midpoint(A, B) → E
7. Rotate(A, (-δ), D) → A'
8. Rotate(B, (-δ), D) → B'
9. Rotate(C, (-δ), D) → C'
10. Polygon(A', B', C') → poly1', c', a', b'
11. Rotate(A, ε, E) → A'_1
12. Rotate(B, ε, E) → B'_1
13. Rotate(C, ε, E) → C'_1
14. Polygon(A'_1, B'_1, C'_1) → poly1'_1, c'_1, a'_1, b'_1
15. Angle(C'_1, A, B) → η
16. Angle(A', C', B') → ζ