From control systems: I am asked to find the value of K that gives the closed loop damping ratio of 1/sqrt2. The value for the complimentary sensitivity is T(S)=(2KS +4K)/(s^3 +162S^2 +(320+2K)S +4K) so how do I find the value for K? I tried putting it in the general equation, but it wont fit since on the bottom, there is a s^3 term, and on the top, there is a s term. If it is not allowed on physics forums to give a proper answer, then please can you just lead me in the right direction? My notes have nothing in and I can't find anything online! Thanks!