A transfer function is known to have the form "2s/(s^2 + cs + d)." Use the following facts to perform function identification, that is, to find constants a, b, c, d:
i) The steady-state response to a unit step is 2.
ii) The steady-state response to the input Asin(2t) is zero.
iii) The transient response is critically damped (ζ = 1).
