Problem $4(6$pts$)$: The supports or connections are to be assumed as stated.

Classify each of the structures as:

$($a$)$ statically determinate,

$($b$)$ statically indeterminate,

$($c$)$ stable, or

$($d$)$ unstable.

If indeterminate, specify the degree of indeterminacy: $\backslash (\backslash$mathrm$\{$n$\}=\backslash )$