Determine whether ab←→ and cd←→− are parallel, perpendicular, or neither. a(−1, −4), b(2, 11), c(1, 1), d(4, 10)

Slope of AB
m = (y2 - y1)/(x2 - x1)
m = (11 - (-4))/(2 - (-1))
m = (11 + 4)/(2 + 1)
m = 15/3
m = 5
The slope of line AB is 5

Slope of CD
m = (y2 - y1)/(x2 - x1)
m = (10 - 1)/(4 - 1)
m = 9/3
m = 3
The slope of CD is 3

Since the two slopes are not equal, this means the lines are not parallel.
Since (slope of AB)*(slope of CD) = 5*3 = 15 is not equal to -1, this means the lines are not perpendicular

Neither (not parallel; not perpendicular)