Drawing the vectors of each force acting on a node, in a nose to tail fashion will show the resultant force.

(The length of each side is proportional to a force and the angles match the angles of the structure or the angles of the forces.)

Should the lines form a closed polygon, then the forces are balanced around the point.

Knowing the above structure is in equilibrium and the direction of the forces, the length of the sides of the closed triangle indicate the relative values of each force.