Answer
If $\mathbf{v}\cdot \mathbf{w}=0$, then the vectors $\mathbf{v}$ and $\mathbf{w}$ are orthogonal.
Work Step by Step
Dot product of two vectors is given as
$\mathbf{v}\cdot \mathbf{w}=\left| \mathbf{v} \right|\left| \mathbf{w} \right|\cos \theta $
where $\theta $ is the angle between the vectors $\mathbf{v}$ and $\mathbf{w}$.
The dot product between $\mathbf{v}$ and $\mathbf{w}$ is zero if the angle between them is $90{}^\circ $, which implies that the vectors are orthogonal to each other.
