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 magnitude, collinear, and oppose in direction.
Аксиома 4.....
Аксиома 5. .....
Аксиома 6 - затвердевания (пропустил, см. теперь книги..) - спасибо за замечание Т. Алексеевой