82 STATICS. [138. 



138. Exercises. 



(1) Show that the moment of a couple can be represented by the 

 area of the parallelogram formed by the two forces of the couple, or 

 by twice the area of the triangle formed by joining any point on the 

 line of one of the forces to the ends of the other force. 



(2) Show that the sum of the moments of two forces forming a couple 

 is the same for any point in the plane of the couple. 



(3) Show, by means of Arts. 129-131, how to combine any number 

 of couples situated in the same plane, or in parallel planes. 



(4) Find the resultant of two couples situated in non-parallel planes, 

 without using the vectors of the couples. 



