Given two circles with centres c1 and c2, both radius 1, the points of
intersection is the points p that satisfy:
(Note that vectors and points are essentially the same, so we can for
example take the dot product of two points by summing the products of the
components (i.e. coordinates.))
||p-c1|| + ||p-c2|| = 2
This should be fairly straightforward, i think.
5k.
