$($f$)$ The space truss has roller supports at B$,$ C$,$ and D and is subjected to a vertical force $F=250N$ at A$.$

$($i$)$ What are the reactions at the roller supports?

$(4)$

$($ii$)$ Find the axial forces in the members $BC,CD$ and $CA$ and specify if the members are in tension $($T$)$ or in compression $($C$).$

$(6)$