Triangle Law And Polygon Law

polygon law of vector addition:

If several vectors are represented both in magnitude and direction as the adjacent sides of a polygon taken in order then the closing side taken in reverse order represents the resultant both in magnitude and direction. (or) Polygon law can also be stated like this. If the vector sum of several vectors is a null vector, then they can be represented both in magnitude and direction as the adjacent sides of a closed polygon taken in order \( \overline P + \overline Q + \overline R + \overline S + \overline T = \overline 0 \)  
            

Note:
1. If n forces each of same magnitude are acting at a point with the angle 360/n between them then the resultant is zero.
2. If n-1 forces of equal magnitude are acting at a point such that each vector makes an angle 360/n with the preceding one then the magnitude of resultant force is equal to the magnitude of force acting.