$\"\"$

Observe the figure :

The vectors are $\"\"$ and $\"\"$ .

Find the dot product of $\"\"$ .

The dot product of two vectors $\"\"$ and $\"\"$ is $\"\"$ .

Susbtitute $\"\"$ and $\"\"$ .

$\"\"$

$\"\"$ .

Therefore, the correct choice is option $\"\"$ .

$\"\"$

The correct choice is option $\"\"$ .