Before the solution of the problem, note the condition of the job. Will watertite the specified schema, frames, beams, trusses, arches in strictly selected scale. Indicate on your diagram all dimensions and external loads. If a given numeric value, they also should sign. The scheme will watertite using drawing tools, given all of the parameters. All characteristic points of the mark alphabet and the numerical values of the dimensions, loads and support reactions necessarily indicate their values.
Proceed to the determination of reactions in sealing. This can be done by making the equation of moments about any point in the specified schema. Typically, a point is selected so that problem was solved in the simplest way. At the selected point can be applied to reactions that are unknown, ie, they are temporarily considered equal to zero.
Select the direction when setting up the equation of moments. In most cases in structural mechanics accept for a positive direction counterclockwise. If the response will turn out negative, then do not be afraid: it means that it is in the opposite direction. But remember that the further solution of the task is always taken into account the sign, which was the result of your calculation.
Determine the reaction at the sealing is not in one part of the schema. Reactions are determined, given all that is given in the problem initially. In any case, do not use this method, as symmetry, as it does not work in this case.
To check whether the computed reaction in terminations is possible, making the equation the sum of the moments on the axis X or Y. If the right decision you should get zero. Remember that making such equations you consider distributed load and strength, and even those reactions that were unknown. If you don't take into account at least one of the loads, the equation will not be zero, and all calculations will be performed again.