What conditions are necessary and sufficient for the balance of a solid?

For the equilibrium of a rigid body, the following conditions are necessary and sufficient:
1) The geometric sum of external forces applied to it is zero:
F1 + F1 + F3 + … = 0
2) The sum of the moments of all external forces acting on the body relative to any axis is zero:
M1 + M2 + M3 + … = 0

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