Which one of the following is the solution for 𝑐𝑜𝑠2𝑥 + 2𝑐𝑜𝑠𝑥 + 1 = 0

Q. Which one of the following is the solution for 𝑐𝑜𝑠²𝑥 + 2𝑐𝑜𝑠𝑥 + 1 = 0, for values of 𝑥 in the range of 0^° < 𝑥 < 360^°?

             (A) 45°              (B) 90°                        (C) 180°                      (D) 270°

Ans: 180°