MathDB
is greater than $\frac{2}{3}$ of area of $ABC$

Source: Moldova TST 1999

August 7, 2023
geometry

Problem Statement

Let ABCABC be a triangle. Show that there exists a lin ll in the plane of ABCABC such that the overlapping area of ABCABC and ABCA^{'}B^{'}C^{'}, the symmetric of ABCABC with respect to ll, is greater than 23\frac{2}{3} of area of ABCABC.