3sinx+1=sinx
2sinx+1=0
2sinx=-1
sinx=-1/2
x=sin^-1 (1/2) = 30 = [tex] \pi [/tex]/6 (when finding the inverse, always take the positive value, ignore the negative sign)
x is therefore negative in 3rd and 4th quadrant
Therefore values of x are:
180+30=210 = 7[tex] \pi [/tex]/6
360-3=330 = 11[tex] \pi [/tex]/6