Addition of several force.
If more than two forces are to be
added.
successive applications of the parallelogram law can be carried
out in order to obtain the resultant force.
For example. if three forces F1,f2,f3 act at a point 0, Fig 2-9, the resultant of any two of the forces is found.
say, F1+F2--and then this resultant is added to the third force,
yielding the resultant of all three forces: i.e ., FR = (F1 + F2)+F3.
Using the parallelogram law 10 add more than two forces, as shown here, often
requires extensive geometric and trigonometric calculation to determine
the numerical values for the magnitude and direction of the resultant.
Instead, problems of this type are easily solved by using the "rectangular-component
method." which is explained in Sec. 2.4.