A rigid bar ABCD is supported by two bars as shown in Figure $3.$

There is no strain in the vertical bars before load $P$ is applied.

After load $P$ is applied, the normal strain in rod $(1)$ is $-570\frac{m}{m}.$

Determine:

$($a$)$ the normal strain in rod $(2).$

$($b$)$ the normal strain in rod $(2)$ if there is a $1-$mm gap in the

connection at pin C before the load is applied.

$($c$)$ the normal strain in rod $(2)$ if there is a $1-$mm gap in the

connection at pin B before the load is applied.

Figure $3$