Cost(2Π-x) +sin(Π/2+x) =√2

Question

Cost(2Π-x) +sin(Π/2+x) =√2

Answer 1

Cos (2π-x)=cos (-x)=cosx
sin (π/2+x)=cosx
cos (2π+x)+sin (π/2+x)=cosx+cosx=2cosx
2cosx=√2
cosx=√2/2
x=+-π/4+2πn n - целое