Решение
cos(π/2 - 2x) + sinx = 0
sin2x + sinx = 0
2sinx*cosx + sinx = 0
sinx * (2cosx + 1) = 0
1) sinx = 0
x = πk, k ∈ Z
2) 2cosx - 1 = 0
cosx = 1/2
x = (+ -) arccos(1/2) + 2πn, n ∈ Z
x = (+ -) (π/3) + 2πn, n ∈ Z
Ответ: x = πk, k ∈ Z ; x = (+ -) (π/3) + 2πn, n ∈ Z