$\"\"$

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

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

Substitute $\"\"$ and $\"\"$ in the above equation.

$\"\"$

Since $\"\"$ , vectors $\"\"$ and $\"\"$ are not orthogonal.

$\"\"$

$\"\"$ ; $\"\"$ and $\"\"$ are not orthogonal.