Provide an Appropriate Response $\cos 2 \theta = \sqrt { 3 }$

Essay

Provide an appropriate response.
-Explain what is wrong with the following solution for the equation $\cos 2 \theta = \sqrt { 3 }$ in the interval $[ 0,2 \pi )$ .
$$\begin{array} { l } \cos 2 \theta = \sqrt { 3 } \\\cos \theta = \frac { \sqrt { 3 } } { 2 } \\\theta = \frac { \pi } { 6 } \text { or } \theta = \frac { 11 \pi } { 6 }\end{array}$$