MathDB
locus inside an equilateral triangle (2007 HOMC Senior Q8)

Source:

July 18, 2019
geometryLocusEquilateral

Problem Statement

Let ABCABC be an equilateral triangle. For a point MM inside ABC\vartriangle ABC, let D,E,FD,E,F be the feet of the perpendiculars from MM onto BC,CA,ABBC,CA,AB, respectively. Find the locus of all such points MM for which FDE\angle FDE is a right angle.