$\"\"$

The vector is $\"\"$ .

The standard form of the vector is $\"\"$ .

Compare $\"\"$ with $\"\"$ .

$\"\"$ .

Direction angle is $\"\"$ .

Substitute $\"\"$ in formula.

$\"\"$

Since the point $\"\"$ lies in the third quadrant.

Thus, the direction angle is

$\"\"$

Direction angle is $\"\"$ .

$\"\"$

Direction angle is $\"\"$ .