two parallel lines are drawn here. namely AB and A'B'. from definition parallel lines are equidistant and that means the distance between them is the same at all points. therefore, the distance between BB' is 42.45 and also check the distance between AA' is 42.55 as well.

1. draw the cartesian plane and then draw two lines going in the same direction and having the same distance between them and measure to create parallel lines in the end.