BALKAN-SL 2014 G3

Let $\triangle ABC$ be an isosceles. $(AB=AC)$ .Let $D$ and $E$ be two points on the side $BC$ such that $D\in BE$ , $E\in DC$ and $2\angle DAE = \angle BAC$ .Prove that we can construct a triangle $XYZ$ such that $XY=BD$ , $YZ=DE$ and $ZX=EC$ .Find $\angle BAC + \angle YXZ$ .