Resultant Force

The resultant force of concurrent forces in space can be represented by a force vector, R, in three dimensional space.

The most practical way of determining the resultant force in space is to add up their rectangular components respectively:

Imply:

 

Therefore:

And similarly, the resultant force vector, R, can be expressed as:

Force Equilibrium

According to Newton's first law of motion, when a particle is in equilibrium, the resultant of all the forces acting on it is zero. That is

And graphically in the form of force polygon,

, imply