Tacnode

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A tacnode at the origin of the curve defined by (x2+y2 −3x)2−4x2(2−x)=0
A tacnode at the origin of the curve defined by (x2+y2 −3x)2−4x2(2−x)=0

A tacnode is a point where two (or more) osculating circles to the curve at that point are tangent.

For example, the Links curve with equation (x2 + y2 − 3x)2 − 4x2(2 − x) = 0 has a tacnode at the origin.

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