$\"\"$

The trigonometric equation is $\"\"$ .

Consider $\"\"$ .

Multiply each side by $\"\"$ .

$\"\"$

Apply inverse property : $\"\"$ .

$\"\"$

Using the calculator : $\"\"$ .

$\"\"$ .

Since the desired angle in QI, the reference angle of $\"\"$ . $\"\"$

The angle is $\"\"$ .