A) Cos²β(1-Sin²β)=Cos²β*Cos²β=
![Cos^{4}](https://tex.z-dn.net/?f=Cos%5E%7B4%7D%20)
β
б) Sin²β(Sin²β+Cos²β)=Sin²β
в) Sin²β/Cos²β * Cos²β/Sin²β - Sin²β=1-Sin²β=Cos²β
г) Sin²β/(-Cos²β)=-Tg²β
Решение смотри в приложении
1) x² + 6x - 16 = 0
x² + 6x + 9 - 25 = 0
(x + 3)² - 5 = 0
(x + 3 - 5)(x + 3 + 5) = 0
x + 3 - 5 = 0
x + 3 + 5 = 0
x = 2
x = -8
Ответ: х = -8; 2.
2) x² - 4x - 12 = 0
x² - 4x + 4 - 16 = 0
(x - 2)² - 4² = 0
(x - 2 - 4)(x - 2 + 4) = 0
x - 6 = 0
x + 2 = 0
x = 6
x = -2
Ответ: х = -2; 6.