Example 6: Determine the resultant moment of the two forces about line aa.
(Move the mouse pointer over the figure to see the moment
vector)
Solution: We begin by calculating the
moment of force 
about
line aa as
where
Using the triple scalar product, we find
Repeating the calculations for 
, yields
where
Therefore, the resultant moment about line aa is
We can express the moment resultant in Cartesian vector form as
