Two lines are parallel when their slopes are the same
Two lines are perpendicular when the product of their slopes is -1
Two lines are intersect when their slopes are different
Let's define our slopes as m1 and m2, != means not equal
Solution:
1) m1 = m2 Parallel
2) m1*m2=-1 Perpendicular
3) m1*m2=-1 Perpendicular
4) m1=m2 Parallel
5) m1=m2 (-4 = -4) Parallel
6) m1 != m2 Neither
7) m1 != m2 Neither
8) m1*m2=-1 Perpendicular