If two forces, acting simultaneously on a particle, be represneted by the two adjacent sides of a parallelogram, their resultant may be represented in magnitude and direction by the diagonal of the parallelogram which passes through their point of intersection.

Parallelogram Law of Forces

Two tensile forces acting at an angle 120 degree between them. The bigger force is 40KN. The resultant is perpendicular to the smaller force. Find the smaller force and the resultant force.