已知向量\( \overrightarrow{a}=(2\sin θ,1)\),\( \overrightarrow{b}=(2\cos θ,-1)\),其中\(θ∈(0, \dfrac {π}{2})\).
\((1)\)若\( \overrightarrow{a}⊥ \overrightarrow{b}\),求角\(θ\)的大小;
\((2)\)若\(| \overrightarrow{a}- \overrightarrow{b}|=2| \overrightarrow{b}|\),求\(\tan θ\)的值.