Solve the Equation on the Interval [0, 2π) $f ( x ) = 2 \cos \theta + 1$

Multiple Choice

Solve the equation on the interval [0, 2π) .
-Suppose $f ( x ) = 2 \cos \theta + 1$ . Solve $f ( x ) = 0$ .

A) $\frac { \pi } { 3 } , \frac { 5 \pi } { 3 }$
B) $\frac { \pi } { 2 } , \frac { 3 \pi } { 2 }$
C) $\frac { 3 \pi } { 2 }$
D) $\frac { 2 \pi } { 3 } , \frac { 4 \pi } { 3 }$