7.
已知\(A,B,C\)为\(\Delta ABC\)的三个内角,向量\(\overrightarrow{m}\)满足\(|\overrightarrow{m}|=\dfrac{\sqrt{6}}{2}\),且\(\overrightarrow{m}=(\sqrt{2}\sin \dfrac{B+C}{2},\cos \dfrac{B-C}{2})\),若\(A\)最大时,动点\(P\)使得\(||\overrightarrow{PB}|,|\overrightarrow{BC}|,|\overrightarrow{PC}|\)成等差数列,则\(\dfrac{\overrightarrow{|PA|}}{\overrightarrow{|BC|}}\)的最大值是\((\) \()\)