Verified answer

1) cos(x)=0

x=π/2+πk, k∈z

2) tg(x)=0

x=πk, k∈z

3) ctg(x)=0

x= π/2+πk, k∈z

4) sin(x)=0

x=πk, k∈z

5) sin(x)=1

x=π/2 +2πk, k∈z

6) sin(x)=1/2

x=, k∈z

7) cos(x)= -1

x=π+2πk, k∈z