1) 3sinx=1, sinx=1/3, x=(-1)^n*arcsin1/3+πn, n∈Z
2)2cosx+1=0, cosx=-1/2, x=±arccos(-1/2)+2πn,
x=±(π-arccos1/2+2πn,
x=±(π-π/3)+2πn,
x=±2π/3+2πn, n∈Z
1) 3sinx=1, sinx=1/3, x=(-1)^n*arcsin1/3+πn, n∈Z
2)2cosx+1=0, cosx=-1/2, x=±arccos(-1/2)+2πn,
x=±(π-arccos1/2+2πn,
x=±(π-π/3)+2πn,
x=±2π/3+2πn, n∈Z