the quickest way to tell if a line is perpendicular is to find the slope, so you'll need to get the slope for both lines
PQ = ((-8) - (-9))/(2 - 0) = 1/2
and, for reference, a perpendicular slope is the negative reciprocal of the original (so we're looking for -2)
RS = (3 - 4)/(3 - 1) = -1/2
so, no, these two lines aren't perpendicular because the slope of RS is only the negative of PQ, not the negative reciprocal.
