When according to the design specifications we find a desired minimum natural frequency for our control system:

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We can never show this limit in the root locus, but we can do it in the step response graph

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We can show this limit as a vertical line in the root locus

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We can show this limit as a circle in the root locus

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We can show this limit as a couple of lines giving an angle from the real axis in the root locus

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