$\"\"$

The trigonometric equation is $\"\"$ .

Find the value of $\"\"$ which satisfy the above equation, where $\"\"$ in the interval $\"\"$ .

Graph :

Graph the functions $\"\"$ and $\"\"$ , plot the point where the both functions are intersect.

$\"\"$

Observe the graph $\"\"$ and $\"\"$ intersect each other at $\"\"$ and $\"\"$ .

Thus, $\"\"$ when $\"\"$ and $\"\"$ .

$\"\"$

$\"\"$ when $\"\"$ and $\"\"$ .