Problem:
Circles and intersect at points and . Segment is tangent to at and to at , and is closer to than . Point is on such that , and point is on such that . Given that and , find the ratio .
Problem:
Circles and intersect at points and . Segment is tangent to at and to at , and is closer to than . Point is on such that , and point is on such that . Given that and , find the ratio .

Let be the fourth vertex of parallelogram . The midpoint of is the intersection of the diagonals of this parallelogram. Because has equal power with respect to the two circles and , it lies on , the circles' radical axis. Therefore, lies on as well.
Using a series of parallel lines and inscribed arcs, we have:
where the last equality follows from the fact that .
We also know that , so triangles and are similar. By the spiral similarity theorem, triangles and are similar, too.
By analogous reasoning, triangles and are similar. Then we have:
where the last equality holds because is a parallelogram. Using the Law of Sines, the last expression equals .