The feedback system shown below oscillates at 2 rad/s when

A system with transfer function g(s) = $${{\left( {{s^2} + 9} \right)\left( {s + 2} \right)} \over {\left( {s + 1} \right)\left( {s + 3} \right)\left( {s + 4} \right)}},$$ is excited by $$\sin \left( {\omega t} \right).$$ The steady-state output of the system is zero at

The transfer function of a compensator is given as $${G_C}(s) = {{s + a} \over {s + b}}.$$

$${G_C}(s)$$ is a lead compensator if

The transfer function of a compensator is given as $${G_C}(s) = {{s + a} \over {s + b}}.$$

The phase of the above lead compensator is maximum at