1) Coplanar concurrent forces are forces that act in the same plane and meet at a single point. 2) For a system of coplanar concurrent forces to be in equilibrium, the algebraic sum of the forces along two perpendicular directions must be zero. 3) There are analytical and graphical methods to find the resultant force of a coplanar concurrent forces system, including the parallelogram law, resolution of forces, triangle law, and polygon law of forces.