5) cos(x + $$ \frac{\pi}{3} $$) = 0
x + $$ \frac{\pi}{3} $$ = $$ \frac{\pi}{2} $$ + \u03c0n, n ∈ Z
x = $$ \frac{\pi}{2} $$ - $$ \frac{\pi}{3} $$ + \u03c0n, n ∈ Z
x = $$ \frac{\pi}{6} $$ + \u03c0n, n ∈ Z
Ответ: x = $$ \frac{\pi}{6} $$ + \u03c0n, n ∈ Z