Question 81
The vertices of the convex quadrilateral $ABCD$ They are located in a circumference. its diagonals $AC$ y $BD$ They are cut at the point $E$. be $O_{1}$ The center of the circle inscribed in the triangle $ABC$, y $O_{2}$ The center of the circle inscribed in the triangle $ABD$. the straight $O_{1}O_{2}$ cut to $EB$ on $M$ y a $EA$ on $N$. prove that the triangle $EMN$ is isosceles.