Verified answer

[tex]\displaystyle\bf\\-3Sinx=1\\\\Sinx=-\frac{1}{3} \\\\x=(-1)^{n}arcSin\Big(-\frac{1}{3} \Big)+\pi n,n\in Z\\\\\\x=(-1)^{n+1} arcSin\frac{1}{3} +\pi n,n\in Z[/tex]