Lines L1 and L2 are parallel.
Lines L1 and L4 are NOT perpendicular. :)
L1 and L2 are Parallel because they do not intersect. We say that two lines on the same plane are parallel to each other if they never intersect each other, ragardless of how far they are extended on either side.
Lines L1 and L4 are NOT perpendicular because they do NOT intersect at an 90° angle. In geometry, perpendicular lines are defined as two lines that meet or intersect each other at right angles or 90°. A good example of a perpendicular line intersecting correctly is the letter T.