Determine if the lines L1 and L2 passing through the give pair of points are parallel, perpendicular, or neither. L1: (-2, -3), (1, 3) and L2: (4, 5), (-4, -11)

Answer 1

just figure their slopes.
If the slopes are the same, L1║L2.
If their product is -1, then L1┴L2.
Otherwise, neither.