12
sin(x-π/4)=0
x-π/4=πn
x=π/4+πn,n∈z
14
sin(x-π/3)=0
x-π/3=πn
x=π/3+πn,n∈z
16
tg(π/3-x)=0
-tg(x-π/3)=0
x-π/3=πn
x=π/3+πn,n∈z
18
cosx=-√2/2
x=+-3π/4+2πn,n∈z
20
cos(x-π)=-1
-cosx=-1
cosx=1
x=2πn,n∈z
22
1/2*sin2x=√3/4
sin2x=√3/2
2x=(-1)^n*π/3+πn
x=(-1)^n*π/6+πn/2,n∈z
24
1-cos(x/3+π/3)=1/2
cos(x/3+π/3)=1/2
x/3+π/3=+-π/3+2πn
x/3=-2π/3+2πn U x/3=2πn
x=+-2π+6πn U x=6πn,n∈z
26
tg3x=4
3x=arctg4+πn
x=1/3*arctg4+πn/3,n∈z
28
cosxcos2x=0
cosx=0⇒x=π/2+πn,n∈z
cos2x=0⇒2x=π/2+πn⇒x=π/4+πn/2,n∈z
30
2cos²x=1
2cos²x-1=0
cos2x=0
2x=π/2+πn⇒x=π/4+πn/2,n∈z