1) Draw a circle a.
2) Fix a point A, not on a.
3) Fix a segment of length d.
4) Consider a point B, moving on a.
5) Construct the points X, Y , on AB, such that XB=BY = d.
6) The locus of X, Y , for B moving on a, is the conchoid of the circle a.
Modify the length of segment d, to see the various shapes this curve takes.
Change the length of d and the location of point A to see how the locus changes its shape. For a similar construction, using a line, instead of a circle, look at Nicomedes.html .