1. The problem statement, all variables and given/known data Find all possible solutions: 2cos22θ = 1 - cos2θ 3. The attempt at a solution I know all my arithmetic is correct, but when it comes to giving the answer, I'm not sure how to write it. 2cos22θ + cos2θ - 1 = 0 (2cos2θ - 1)(cos2θ + 1) = 0 2cos2θ = 1 cos2θ = 1/2 2θ = ∏/3 cos2θ = -1 2θ = ∏ So θ is equal to ∏/6 and ∏/2 But the solutions are supposed to be: ∏/6 + ∏n 5∏/6 + ∏n ∏/2 + ∏n And I don't understand why. Can someone explain it to me please?