# Where is xml?

Geometry Level 5

$$\triangle ABC$$ satisfies $$AB=AC$$, $$\angle BAC=36^{\circ}$$ and has circumradius $$2$$. Let $$D$$ be a point on the circumcircle $$ABC$$ such that $$OD||BC$$, where $$O$$ is the circumcenter. Project $$D$$ onto $$AB,AC$$ to obtain $$E,F$$, i.e. $$DE\perp AB, DF\perp AC$$.

Suppose $$H$$ is the orthcenter of $$ABC$$. Then the area of $$\triangle HEF$$ can be expressed as $$\sqrt {\frac {x+\sqrt {m}}{l}}$$, where $$x,m,l$$ are positive integers, and $$m$$ is square-free. Find $$xml$$

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