Chapter 13 - Vector Geometry - 13.3 Dot Product and the Angle Between Two Vectors - Exercises - Page 667: 62

7

Component of $\textbf{u}$ along $\textbf{v}$= $\frac{\textbf{u}\cdot\textbf{v}}{||\textbf{v}||}$ $\textbf{u}\cdot\textbf{v}=⟨3,0,9⟩\cdot ⟨1,2,2⟩=3(1)+0(2)+9(2)=21$ $||\textbf{v}||=\sqrt {1^{2}+2^{2}+2^{2}}=3$ Therefore, Component of $\textbf{u}$ along $\textbf{v}$ $=\frac{21}{3}=7$