IMO Shortlist 1993 problem G3
Let triangle
be such that its circumradius is
Let
be the inradius of
and let
be the inradius of the orthic triangle
of triangle
Prove that
%V0
Let triangle $ABC$ be such that its circumradius is $R = 1.$ Let $r$ be the inradius of $ABC$ and let $p$ be the inradius of the orthic triangle $A'B'C'$ of triangle $ABC.$ Prove that $$p \leq 1 - \frac{1}{3 \cdot (1+r)^2}.$$
Source: Međunarodna matematička olimpijada, shortlist 1993