$\"\"$

\

The trigonometric equation is $\"\"$ and the interval is $\"\"$ .

\

Since $\"\"$ function is negative in third quadrant.

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

The general solution of $\"\"$ is $\"\"$ , where $\"image\"$ is an integer.

\

The general solution is $\"\"$ , where $\"image\"$ is an integer.

\

If $\"image\"$ , then $\"\"$ ,

\

If $\"image\"$ , then,

\

$\"\"$

\

Thus, the solutions are $\"\"$ and $\"\"$ in the interval $\"\"$ . $\"\"$

\

The solutions are $\"\"$ and $\"\"$ in the interval $\"\"$ .