The closed loop transfer function of a control system is given by $\frac{C(s)}{R(s)}=\frac{1}{s+1}$. for the input $r(t)=\sin\;t$ the steady state response $c(t)$ is ___________
- $1$
- $\frac{1}{\sqrt{2}} \cos t$
- $\frac{1}{\sqrt{2}} \sin (t+\frac{\pi}{4})$
- $\frac{1}{\sqrt{2}} \sin (t-\frac{\pi}{4})$