The dot product of two vectors equals $\overrightarrow{u}\cdot \overrightarrow{v}=\text{‖}\overrightarrow{u}\text{‖}\text{‖}\overrightarrow{v}\text{‖}\cos \alpha$, where $\alpha$ is the angle between the vectors $\overrightarrow{u}$ and $\overrightarrow{v}$.