余弦与正弦加法定理

GeoGebra 命令及参数

1. Intersect(xAxis, yAxis) → A
2. Point(yAxis) → B_1
3. Circle(A, B_1) → c
4. Point(c) → C_1
5. Rotate(C_1, (α + β)°, A) → E
6. Rotate(C_1, β°, A) → C'_1
7. Line(A, C'_1) → f
8. Line(A, C_1) → g
9. Line(A, E) → h
10. OrthogonalLine(E, f) → i
11. Intersect(f, i) → D
12. OrthogonalLine(D, g) → j
13. Intersect(g, j) → C
14. Polygon(A, C, D) → poly1, d, a, e
15. Polygon(A, D, E) → poly2, c', a_1, d_1
16. Angle(poly2) → γ, δ, ε
17. Angle(poly1) → ζ, η, θ
18. OrthogonalLine(E, g) → k
19. OrthogonalLine(D, yAxis) → l
20. Intersect(h, l) → G
21. Intersect(g, k) → B
22. Intersect(k, l) → F
23. Distance(A, B) → distanceAB
24. Segment(E, B) → n
25. Segment(D, F) → m
26. Distance(E, B) → distanceEB
27. Angle(D, F, E) → ι