选修\(4-1\):几何证明讲
已知\(\triangle ABC\)中,\(AB=AC\),\(D\)是\(\triangle ABC\)外接圆劣弧\( \hat AC\)上的点\((\)不与点\(A\),\(C\)重合\()\),延长\(BD\)至\(E\).
\((1)\)求证:\(AD\)的延长线平分\(∠CDE\);
\((2)\)若\(∠BAC=30^{\circ}\),\(\triangle ABC\)中\(BC\)边上的高为\(2+ \sqrt {3}\),求\(\triangle ABC\)外接圆的面积.