## Precalculus (6th Edition) Blitzer

Assume vector A: $\mathbf{A}=\mathbf{i}+\mathbf{j}+\mathbf{k}$ Here i, j and k are the unit vectors with magnitude $1$. Now, consider the dot product of this unit vectors i with itself. \begin{align} & \mathbf{i}\cdot \mathbf{i}=1\times 1\times \cos 0{}^\circ \\ & =1 \end{align} Thus the given statement makes sense.