Find All Solutions in the Interval [0, 2π]
- $$\cos ^ { 2 } x + 2 \cos x + 1 = 0$$

Multiple Choice

Find all solutions in the interval [0, 2π]
- $$\cos ^ { 2 } x + 2 \cos x + 1 = 0$$

A) $x = \frac { \pi } { 2 } , \frac { 3 \pi } { 2 }$
B) $x = 2 \pi$
C) $x = \pi$
D) $x = \frac { \pi } { 4 } , \frac { 7 \pi } { 4 }$