Solve the Equation (X in Radians and in Degrees) for All

Multiple Choice

Solve the equation (x in radians and 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.
- $\cos ^ { 2 } x - \cos x = 0$

A) $\left\{ \frac { 5 \pi } { 3 } + 2 n \pi \right\}$
B) $\left\{ \frac { \pi } { 2 } + 2 n \pi \right\}$
C) $\{ \pi + 2 n \pi \}$
D) $\left\{ 2 \mathrm { n } \pi , \frac { \pi } { 2 } + \mathrm { n } \pi \right\}$