Write the condition of equilibrium when three forces act on a particle.

(N/A) For a particle to be in equilibrium under the action of three forces $\vec{F_1}$,$\vec{F_2}$,and $\vec{F_3}$,the vector sum of these forces must be zero.
Mathematically,this is expressed as: $\vec{F_1} + \vec{F_2} + \vec{F_3} = 0$.
Geometrically,this means that the three force vectors,when placed head-to-tail,must form a closed triangle. This is known as the Triangle Law of Equilibrium.