IMO Shortlist 1987 problem 10
Avg:
Avg:
Let
and
be two spheres with distinct radii that touch externally. The spheres lie inside a cone
, and each sphere touches the cone in a full circle. Inside the cone there are
additional solid spheres arranged in a ring in such a way that each solid sphere touches the cone
, both of the spheres
and
externally, as well as the two neighboring solid spheres. What are the possible values of
?
Proposed by Iceland.








Proposed by Iceland.
Izvor: Međunarodna matematička olimpijada, shortlist 1987