Answer:




AD║BC
AB║DC
Step-by-step explanation:
The vertices of parallelogram are A(0,0), B(b,0), C(2j,2k) and D(2j-b,2k).
If a line passes though two points, then the slope of the line is

Using this formula the slope of AD is

Using the above formula the slope of BC is

The side AD is parallel to side BC because the slope of two parallel lines are same.
AD║BC
The slope of AB is

The slope of DC is

The side AB is parallel to side DC because the slope of two parallel lines are same.
AB║DC
Therefore the required answers are
,
,
,
, AD║BC, AB║DC.