$4.$ Use the Method of Sections for this problem. Determine the force in members EF$,$ BE$,$ and BC of the truss and state if these members are in tension or compression. $($Note: you will need to solve for the roller forces at D by drawing a FBD of the entire truss system and summing the moment about A$).(6-41)[$BC$=18$kN $($T$)$; EF$=15$kN $($C$)$; BE$=5$kN $($C$)]$