A = (-1, 4), B = (2, -5)
M = (-3, 2), N = (3, 0)
If AB and MN have the same slope, then they are parallel
If the product of the slope of AB and MN is -1, then AB and MN are perpendicular
Let us find their slope and decide they are what
The slope = change of y/change of x
Change of y = yB - yA = -5 - 4 = -9
Change of x = xB - xA = 2 - (-1) = 2 + 1 = 3
The slope of AB = -9/3 = -3
Let us do the same with M and N
Change of y = yN - yM = 0 - 2 = -2
Change of x = xN - xM = 3 - (-3) = 3 + 3 = 6
The slope of MN = -2/6 = -1/3
Since -3 not equal -1/3
AB and MN are not parallel
Since -3 * -1/3 = 1