0 0 votes Which one of the following is the solution for $\cos^2 x + 2 \cos x + 1 = 0$, for values of $x$ in the range of $0^\circ < x < 360^\circ$ $45^\circ$ $90^\circ$ $180^\circ$ $270^\circ$ Calculus gate2018 calculus trigonometry + – gatecse 2.7k points answer comment Share Follow 0 reply Please log in or register to add a comment.