Method of Sections

In the method of sections, a section is of the truss is cut, such that only three unknown forces are required to be computed. Three equilibrium equations for a plane are used to find out three unknown forces. The method of sections has the basic advantage that the force in almost any desired member may be found directly from an analysis of a section which has cut that member.

As an example , consider the truss shown in figure below. Suppose that it is desired to find out forces in member HG, CG and CD.