Solve the Equation (X in Radians and θ in Degrees) $$\cos ^ { 2 } x + 2 \cos x = - 1$$

Solve the equation (x in radians and θ in degrees) for all exact solutions where appropriate. Round approximate answers in radians to four decimal places and approximate answers in degrees to the nearest tenth.
- $$\cos ^ { 2 } x + 2 \cos x = - 1$$

A) $\{ \mathrm { n } \pi \}$
B) $\{ \pi + 2 n \pi \}$
C) $\{ 2 n \pi \}$
D) $\left\{ \frac { \pi } { 2 } + n \pi , 2 n \pi \right\}$

Correct Answer:

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