$(4)$ Consider the structure in Figure $4\mathrm{.}1.$ All members are of negligible weight and all joints are pin

connections. The structure is supported by two hinges at point $G$ and $K$ and one roller at point $A.$

Member $OP$ is subjected to a distributed load and is held by two cables $IO$ and NP$.$ The entire system

is in equilibrium. Answer the following questions.

$(4\mathrm{.}1)$ Find the tension forces in cables $IO$ and $NP.$

$(4\mathrm{.}2)$ Noting that sub$-$structures ABHIG and HJLNM are internally stable, we can treat them as two rigid

bodies with a pin connection at point $H$ and corresponding supports, as illustrated in Figure $4\mathrm{.}2.$

Draw the free body diagrams for sub$-$structures ABHIG and HJLNM$.$

$(4\mathrm{.}3)$ Determine the forces acting on sub$-$structures ABHIG and HJLNM$.$

$(4\mathrm{.}4)$ Once knowing the external forces acting on each sub$-$structure, we can further obtain the forces

in each member of the sub$-$structures. Determine the forces in member $ML$ and $EH.$