2cosx+sqrt3=0 sin (2P-x) - cos (3P/2+x) + 1=0 sin9P/4 cos (-4P/3)

1) 2 * cos (x) = - √3

cos (x) = - √3/2

x = arccos ( - √3/2) + - 2 * π * n, где n - натуральное число

x = 2π / 3 + - 2 * π * n

2) Так как sin (2 * π - x) = - sin (x), cos (3 * π / 2 + x) = sin (x), получим уравнение:

- sin (x) - sin (x) + 1 = 0

sin (x) = 1

x = arxsin (1) + - 2 * π * n

x = π/2 + - 2 * π * n.

3) sin (9 * π / 4) = sin (2 * π + π/4) = sin (π/4) = √2/2;

cos ( - 4 * π / 3) = cos ( - π - π/3) = cos (π/3) = 1/2.