This paper derives simple CAD formulas of three common types of MIC lines: microstrip, CPW (coplanar waveguides) without and with a backing conducting plane. It shows that both the analysis and design formula pair can be derived from the same novel technique of synthetic asymptote. Unlike other curve fitted formulas, the synthetic asymptote formulas are simple, provide good physical insight and only one arbitrary constant. The paper also shows that a combination of the two formula pairs, of a CPW (without conductor backing) and a microstrip line, actually form the formula pair of a CPW with conductor backing. The average errors are less than 2%.