We can fund that distance be taking moments, so the moment of the resultant

force, must be equal to the sum of the moment of the individual forces.

In other words, R times d must be equal to M0,

from which we can calculate the location of the resulting

force from d is equal to M0, divided by the resultant force.

So, here is the equivalent section from the reference manual.

And the conditions for equilibrium, are simply,

that the sum of the forces acting on the body must be equal to 0.

And the sum of the moments about some point, must also be equal to 0.

There were some special cases that we discussed in the static segment.

In two dimensions, for example the first one, collinear forces,

means that the lines of action of all the forces lie on a common line.

And in this case, we have only one independent equilibrium equation,

that the sum of the forces, along the line of axis, action of the forces,

is equal to 0.

The second case, case two, the forces are concurrent at a point.

In other words, the lines of action of all the forces,

pass through some common point, denoted by O here.