Equilibrium of a Member with Three Forces
The condition for equilibrium of a member with three forces can be determined by analyzing the forces acting on the member and ensuring that the sum of all the forces acting on the member is equal to zero.

Key Points:
- When three forces act on a member, they must be concurrent at a single point in order to maintain equilibrium.
- The forces must also be coplanar, meaning they all lie in the same plane.
- The forces can be resolved into their horizontal and vertical components to analyze the equilibrium of the member.
- By applying the equations of equilibrium (ΣFx = 0 and ΣFy = 0), the magnitudes and directions of the forces can be determined to ensure equilibrium.
- The forces must satisfy the condition that the sum of the forces in the x-direction and the sum of the forces in the y-direction are both equal to zero.
In conclusion, for a member to be in equilibrium with three forces, the forces must be concurrent, coplanar, and satisfy the equations of equilibrium. By analyzing the forces and their components, the equilibrium of the member can be determined.