2.
若两个非零向量\( \overrightarrow{a}\),\( \overrightarrow{b}\)满足\(| \overrightarrow{a}+ \overrightarrow{b}|=| \overrightarrow{a}- \overrightarrow{b}|=2| \overrightarrow{a}|\),则向量\( \overrightarrow{a}+ \overrightarrow{b}\)与\( \overrightarrow{a}- \overrightarrow{b}\)的夹角是\((\) \()\)