IMO Shortlist 1982 problem 12
Four distinct circles

, C3 and a line L are given in the plane such that

and

are disjoint and each of the circles

touches the other two, as well as

and

. Assuming the radius of

to be

, determine the distance between its center and
%V0
Four distinct circles $C,C_1, C_2$, C3 and a line L are given in the plane such that $C$ and $L$ are disjoint and each of the circles $C_1, C_2, C_3$ touches the other two, as well as $C$ and $L$. Assuming the radius of $C$ to be $1$, determine the distance between its center and $L.$
Source: Međunarodna matematička olimpijada, shortlist 1982