MathDB
common interior tangent

Source: IMO 1980 Luxembourg, problem 2

May 6, 2004
geometryfunctionareaTriangleIMO Shortlist

Problem Statement

Three points A,B,CA,B,C are such that B]AC[B \in ]AC[. On the side of ACAC we draw the three semicircles with diameters [AB],[BC][AB], [BC] and [AC][AC]. The common interior tangent at BB to the first two semi-circles meets the third circle in EE. Let UU and VV be the points of contact of the common exterior tangent to the first two semi-circles. Denote the area of the triangle ABCABC as S(ABC)S(ABC). Evaluate the ratio R=S(EUV)S(EAC)R=\frac{S(EUV)}{S(EAC)} as a function of r1=AB2r_1 = \frac{AB}{2} and r2=BC2r_2 = \frac{BC}{2}.