0 votes 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 asked Feb 20, 2018 • recategorized Mar 18, 2021 by Lakshman Bhaiya gatecse 1.4k points answer comment Share Follow See all 0 reply Please log in or register to add a comment.