Answer
(a) $3\textbf {i}+4\textbf {j}$ and $8\textbf {i}-6\textbf {j}$
Work Step by Step
If the vectors are perpendicular, their dot product must be zero. In order to find the pair of vectors that is perpendicular, we need to find the dot products of each of the vector pairs.
Part (a)
Dot product$=(3,4)\cdot(8,-6)=3(8)+4(-6)=24-24=0$
Therefore, $3\textbf {i}+4\textbf {j}$ and $8\textbf {i}-6\textbf {j}$ are perpendicular.
Since the vector pair in part (a) is perpendicular, this automatically means that all the other vector pairs are not perpendicular.
