$\"\"$

\

The trigonometric equation is $\"\"$ .

\

Apply cosine sum identity : $\"\"$ .

\

Apply sine sum identity : $\"\"$ .

\

$\"\"$

\

$\"\"$

\

Solve $\"\"$ .

\

$\"\"$

\

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

\

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

\

Now find the solutions on the interval $\"\"$ .

\

If $\"\"$ , $\"\"$ .

\

If $\"\"$ , $\"\"$ .

\

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

\

$\"\"$

\

The solutions of $\"\"$ are $\"\"$ and $\"\"$ on the interval $\"\"$ .