First read the

conchoid writeup. The conchoid of

Nicomedes
is the conchoid associated with the data: a

line, a

point not on the line,
and a

distance.

If we take the line to be *x=a*, the point to be *(0,0)*
and the distance to be *d* then the conchoid has equation:

*(x*^{2}+y^{2})(x-a)^{2}=d^{2}x^{2}

Nicomedes used this curve to solve the problem of trisection of the angle,
one of the three geometric problems of antiquity some time around 180 BC.