oganesbagoyan

Verified answer

7.
sin(x/2) *(cosx+1) =0⇔ [sin(x/2) =0 ; cosx+1=0⇔ [sin(x/2) =0 ; cosx =-1.⇔
 [x/2 =πn ; x = π +2πn ,n∈Z.⇔  [x =2πn ; x = π +2πn ,n∈Z.⇔
[ x =π*(2n) ; x = π*(2n+1) ,n∈Z
⇔x =πk , k∈Z.