6.
如图,在\(\triangle ABC\)中,\(∠ABC\)和\(∠ACB\)的平分线相交于点\(O\),过点\(O\)作\(EF/\!/BC\)交\(AB\)于\(E\),交\(AC\)于\(F\),过点\(O\)作\(OD⊥AC\)于\(D.\)下列四个结论:
\(①∠BOC=90^{\circ}+\)
\(∠A\);\(②\)以\(E\)为圆心、\(BE\)为半径的圆与以\(F\)为圆心、\(CF\)为半径的圆外切;\(③\)设\(OD=m\),\(AE+AF=n\),则\(S_{\triangle AEF}=mn\);\(④EF\)是\(\triangle ABC\)的中位线\(.\)其中正确的结论是
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