MathDB
Isosceles right triangle

Source: Canada 1969, Problem 10

May 14, 2006
geometryrectangle

Problem Statement

Let ABCABC be the right-angled isosceles triangle whose equal sides have length 1. PP is a point on the hypotenuse, and the feet of the perpendiculars from PP to the other sides are QQ and RR. Consider the areas of the triangles APQAPQ and PBRPBR, and the area of the rectangle QCRPQCRP. Prove that regardless of how PP is chosen, the largest of these three areas is at least 2/92/9.