Write the original equation in the standard quadratic form= 0. Factor left side (2cos(t)-1) * (cos(t)+1) = 0. Case 1. 2cos(t) - 1 = 0 ---> cos(t) = ---> t = or t = . Case 2. cos(t) + 1 = 0 ---> cos(t) = -1 ---> t = . ANSWER. The set of solutions is , and , in ascending order.