Question

Помогите, пожалуста:
1. tg2x • ctg2x =
2. cos²x - 1 =
3. - sin²2x - cos²2x =
4. cos3x sin3x =
5. sinx/2 cosx/2 =
6. 1 - 2sin²4x =
7. sin²3x =
8. cosx cos5x + sinx sin5x =
9. cos6x sin8x - sin6x cos8x =
10. 1 + cos5x =
11. sin4x - sin8x =
12. cos3x + cos7x =
13. sin3x • sin5x
14. cos (П/2-ã) =
15. tg (2П - ß) =
16. sin²12° + cos²12° =
17. 2sin45° cos45° =
18. cos²55°/sin²55° =
19. 2tg²12° ctg²12° =
20. cos²26° - sin²26° =
21. sin²35° - cos²35° =
22. 2cos²26° - 1 =
23. - 2sin²57° =
24. cos 25° cos35° - sin25° sin35° =
25. sin49° cos4° - cos49° sin4° =
26. sin15° + sin25° =
27. cos46° - cos22° =
28. sin35° cos35° =
29. sin36° cos36° =
30. 1 - cos68° =
Помогите!)

Answer 1

1. tg2x • ctg2x = 1
2. cos²x - 1 = - Sin²x
3. - sin²2x - cos²2x = -1
4. cos3x sin3x = 1/2*Sin6x
5. sinx/2 cosx/2 =1/2*Sinx
6. 1 - 2sin²4x =Cos8x
7. sin²3x = =?
8. cosx cos5x + sinx sin5x =Сos4x
9. cos6x sin8x - sin6x cos8x =Sin2x
10. 1 + cos5x =Cosπ/2 + Cos5x = 2Cos(π/4 +2,5x)Cos(π/4 -2,5x)
11. sin4x - sin8x = -2Sin2xCos6x
12. cos3x + cos7x =2Cos5xCos2x
13. sin3x • sin5x= 1/2*(Cos2x- Cos8x)
14. cos (П/2-ã) =Sinα
15. tg (2П - ß) = -tgβ
16. sin²12° + cos²12° =1
17. 2sin45° cos45° =Sin90° = 1
18. cos²55°/sin²55° =Ctg²55°
19. 2tg²12° ctg²12° =2
20. cos²26° - sin²26° = Cos52°
21. sin²35° - cos²35° = -Cos70°
22. 2cos²26° - 1 =Cos52°
23. - 2sin²57° = ?
24. cos 25° cos35° - sin25° sin35° =Cos60°= 1/2
25. sin49° cos4° - cos49° sin4° =Sin45° = √2/2
26. sin15° + sin25° =2Sin20°Cos5°
27. cos46° - cos22° = - 2Sin34° Sin12°
28. sin35° cos35° = 1/2*Sin70°
29. sin36° cos36° =1/2Sin72°
30. 1 - cos68° =Cos0 - Cos68° = -2Sin34°Sin34° = -2Sin²34°