Question 142
Be $ABC$ a triangle with $AB = 13$, $BC = 15$ e $AC = 9$. Be $r$ The line parallel to $BC$ traced by $A$. The bisector of the angle $\angle BCA$ cut the line $r$ in $E$ and the bisector of the angle $\angle CBA$ cut $r$ in $F$. Calculate the measure of the segment $EF$.