MathDB
2018-2019 Fall OMO Problem 22

Source:

November 7, 2018

Problem Statement

Let ABCABC be a triangle with AB=2AB=2 and AC=3AC=3. Let HH be the orthocenter, and let MM be the midpoint of BCBC. Let the line through HH perpendicular to line AMAM intersect line ABAB at XX and line ACAC at YY. Suppose that lines BYBY and CXCX are parallel. Then [ABC]2=a+bcd[ABC]^2=\frac{a+b\sqrt{c}}{d} for positive integers a,b,ca,b,c and dd, where gcd(a,b,d)=1\gcd(a,b,d)=1 and cc is not divisible by the square of any prime. Compute 1000a+100b+10c+d1000a+100b+10c+d.
Proposed by Luke Robitaille