Question

Ребят, помогите,пожалуйста с математикой!!!
1. cos (x/4) = - 1
2. 4 sin 5x - 2 = 0

Answer 1

2. sin5x+ (-sin(3pi/2 - 4x)) = 0
sin5x = sin(3pi/2 - 4x)
5x = 3pi/2 - 4x + 2k*pi, k - {0; +-1; ...}
x = pi/6 + 2/9 * k * pi, k - {0; +-1; ...}
5x = pi - [3pi/2 - 4x] + 2k*pi, k - {0; +-1; ...}
x = -pi/2 + 2k*pi, k - {0; +-1; ...}