-sin(2x) =---> -2sin(x)*cos(x) = ---> -2sin(x)*cos(x) - sqrt(3)*sin(x)}}} = 0 ---> = 0 ---> The last equation deploys in two independent equations 1. sin(x) = 0 with the solutions x = 0 and x = . 2. = 0, which is the same as cos(x) = , with the solutions x = and x = . Answer. The set of solutions is {0, , , }.