Non-concurrent forces are forces that do not meet at one point of intersection while acting on the same object. Since they do not intersect at one point, they are not parallel, and the resultant cannot equal zero.
A problem with non-concurrent forces can be solved in a number of ways. One method is to resolve each pair of forces using a graphical, parallelogram or triangle method. This produces a resultant that can be entered into the next equation until all forces have been resolved. An algebraic solution is simpler if the forces can be simplified into components to produce a resultant.