Lami's theorem states that
1
Three forces acting at a point will be in equilibrium
2
Three forces acting at a point can be represented by a triangle, each side being proportional to force
3
If three forces acting upon a particle are represented in magnitude and direction by the sides of a triangle, taken in order, they will be in equilibrium
4
If three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two