Answer
Not orthogonal vectors
Work Step by Step
If $ u \cdot v = 0 $ for two nonzero vectors $u=\left\langle a,b\right\rangle$ and $v=\left\langle c,d\right\rangle$, then $\cos \theta = 0 $ means $\theta= 90°$ and the vectors $u$ and $v$ are called orthogonal vectors.
The dot product is given by:
$u\cdot v=\left\langle a,b\right\rangle\cdot\left\langle c,d\right\rangle=ac+bd$
Now for $-4+3j=\left\langle -4,3\right\rangle$ and $8i-6j=\left\langle 8,-6\right\rangle$ we have
$\left\langle -4,3\right\rangle\cdot\left\langle 8,-6\right\rangle=(-4)(8)+(3)(-6)=-32-18=-50\neq0$
Since $\left\langle -4,3\right\rangle\cdot\left\langle 8,-6\right\rangle\neq0$, therefore the vectors $-4+3j$ and $8i-6j$ are not orthogonal vectors (to each other).
