Question

cos(Pi/2 + 2)-sin(5Pi/2 - 2x)=o

Answer 1

cos(π/2 + 2x) - sin(5π/2 - 2x) = 0
sin2x - cos2x = 0 делим на cos2x ≠ 0, 2x ≠ π/2 + πn, n∈Z ; 
 x ≠ π/4 + πn/2, n∈Z
tg2x - 1 = 0
cos2x = - 1
2x = π + 2πk, k∈Z
x = π/2 + πk, k∈Z