Аксиома 1. Two forces applied at one point of body have as their resultant a force applied at the same point and represented by the diagonal of parallelogram constructed with the two given forces as its sides.
Аксиома 2. The action of a given force system on a rigid body remains unchanged if another balanced force system is added to, or substracted from, the original system.
Аксиома 3. A free rigid body subjected to the action of two forces can be eqilibrium if, and only if, the two forces are equal in magn