Tangent Curves
Two curves both containing the point P are tangent at P if they share the same tangent line at P.
See also
Osculating Curves, Tangent Circles, Tacnode, Tangent LineThis entry contributed by David Terr
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Terr, David. "Tangent Curves." From MathWorld--A Wolfram Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/TangentCurves.html