$($ii$)$ Consider the closed$-$loop control system in Figure $1$ with the following marginally stable plant

G$($s$)=(10)/($s$($s$+4))$

Using the root locus technique, design a phase lag compensator such that the static velocity error

constant K$\_($v$)$ is $50$ without appreciably changing the location of the original closed$-$loop poles, which

are at $-2+-\backslash$sqrt$(6)$jK when G$\_($c$)($s$)=1$