MathDB
constant circle

Source: iran (2003)

March 27, 2004
vectorgeometryangle bisectorgeometry solved

Problem Statement

XOY is angle in the plane.A,B are variable point on OX,OY such that 1/OA+1/OB=1/K (k is constant).draw two circles with diameter OA and OB.prove that common external tangent to these circles is tangent to the constant circle( ditermine the radius and the locus of its center).