Given that two forces and are acting at two points and respectively to form a couple, find the perpendicular distance between the two forces.
is a square of side length 8 cm, where two forces of magnitudes 21 N are acting at and respectively, and their lines of action are in the direction of and respectively. Determine the magnitude of the moment of the couple.
is a rectangle, in which and . Two forces of the same magnitude N are acting at and in the directions of and respectively. Determine the magnitude of the moment of the couple.