$\"\"$

The trigonometric equation is $\"\"$ .

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

Graph :

Graph the functions $\"\"$ .

Draw a line $\"\"$ on the graph.

$\"\"$

Observe the graph $\"\"$ touches the line $\"\"$ at $\"\"$ .

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

$\"\"$

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