If a particle has 3-D forces acting on it and is in static equilibrium, the components of the resultant force (sum of forces in the x-direction, y-direction, and z-direction)
q,
have to equal zero, e.g. 0i 0j 0k
have to sum to zero, e.g., -5i 3i 2k
have to be positive, e.g. 5i 5j 5k
have to be negative, e.g., - 51-5j - 5k