$($a$)$ Classify each of the pin$-$connected structures shown in figure below as statically

determinate or statically indeterminate. The structures are subjected to arbitrary

external loadings that are assumed to be known.

Figure Q$1\mathrm{.}3$

$(2$ marks$)$

$($b$)$ Classify each of the structures in the figure below as stable or unstable. The structures

are subjected to arbitrary external loads that are assumed to be known.