As a structural engineer you are requested to analyse the forces applied on a Roof frame truss structure

of a house. If you know the compression and tension forces $F_A$ and $F_B$ as shown in the figure determine:

The magnitude of the resultant $R$ created by the two forces $F_A$ and $F_B.$

The angle which $R$ makes with the positive $x-$axis.

If the force in member OC is $10$ kN acting to right of point O

what is the value and direction of the minimum force that

is required in member OD to keep the joint $O$ in equilibrium

condition.