Identify parallel, equal length, and perpendicular line segments based on a provided diagram with markings like arrows, tick marks, and square symbols.

Here are the answers based on the markings in the diagram:

a) Which two line segments are parallel to each other?
The arrows on line segments indicate they are parallel.
Segments AE and CD both have a single arrow.

$$\boxed{\text{AE and CD}}$$

b) Which two line segments are equal lengths?
The tick marks on line segments indicate they are equal in length.
Segments AB and BC both have two tick marks.

$$\boxed{\text{AB and BC}}$$

c) Which two line segments are perpendicular to DE?
The square symbols indicate a right angle (perpendicularity).
Segment AE forms a right angle with DE at point E.
Segment CD forms a right angle with DE at point D.

$$\boxed{\text{AE and CD}}$$