Question 119721
SLOPE BETWEEN (-2,5) & (4,-1) IS (-1-5)/(4+2)=-6/6=-1
SLOPE BETWEEN (4,5) & (-2,-1) IS (-1-5)/(-2-4)=-6/-6=1
THESE TWO SLOPES ARE NEGATIVE RECIPRICALS OF EACH OTHER THUS THESE LINES ARE PERPENDICULAR.