## Elementary Linear Algebra 7th Edition

$\left(\frac{5}{13},\frac{-12}{13}\right)$
Given $\mathbf{v}=(12,5)$, then the vector $u=(5,-12)$ is orthogonal to $v$. Now the unit vector indirection of $u$ and orthogonal to $v$ is $$\frac{u}{\|u\|}=\frac{(5,-12)}{\sqrt{25+144}}=\left(\frac{5}{13},\frac{-12}{13}\right).$$