cos(7π+x)=-sqrt(2)/2 или cos(7π+x)=sqrt(2)/2
(7π+x)= ± arccos(-sqrt(2)/2)+2πk, k ∈ [b]Z[/b] или (7π+x)= ± arccos(sqrt(2)/2) +2πn, n ∈ [b]Z[/b]
(7π+x)= ±(π - arccos(sqrt(2)/2))+2πk, k ∈ [b]Z[/b] или (7π+x)= ± (π/4) +2πn, n ∈ [b]Z[/b]
(7π+x)= ±(π - (π/4))+2πk, k ∈ [b]Z[/b] или (7π+x)= ± (π/4) +2πn, n ∈ [b]Z[/b]
(7π+x)= ±(3π/4))+2πk, k ∈ [b]Z[/b] или (7π+x)= ± (π/4) +2πn, n ∈ [b]Z[/b]
x= ±(3π/4))-7π+2πk, k ∈ [b]Z[/b] или x= ± (π/4)-7π +2πn, n ∈ [b]Z[/b]