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path A, B, C;

A := unitcircle shifted (-center unitcircle);

A := A scaled 4cm;

B := unitcircle shifted (-center unitcircle);

B := B scaled 1cm;

%C := (reverse B) shifted (left*1.4cm);

%It works for two paths

fill (reverse B)-- A -- cycle withcolor red;

%fill A -- (reverse B) -- C -- cycle withcolor red;

%When I try the same with three paths, a thin, unwanted line appears

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I'm aware of unfill and I've read somewhere else about using pens instead, but I want to know if a better solution is possible. Thank you in advance.

Regards,

Jairo :)