Suppose L does not intersect the circle O(R). Let H′ be the orthogonal projection
of O on the line L. Set up a Cartesian coordinates with origin at H′
, y-axis
along L, and positive x-axis along the half-line H′O. If the point O has coordinates
(k0, 0) for k0 > R, the circle O(R) has equation (x − k0)
2 + y
2 = R2
,