Circuminscribed
Given two closed curves, the circuminscribed curve is simultaneously inscribed in the outer one and circumscribed on the inner one.
See also
Circumscribed, Inscribed, Poncelet's Porism, Steiner ChainExplore with Wolfram|Alpha
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Cite this as:
Weisstein, Eric W. "Circuminscribed." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Circuminscribed.html